Golf club head and golf club

1. A golf club head comprising:

a head main body provided with a recessed part on the external surface thereof;

a weight member which is mounted in said recessed part and which is formed of a material having a specific gravity greater than that of the head main body, the weight member being made of an alloy;

a first addition member mounted on an external side of the weight member while abutting an external surface of said weight member, a base of said first addition member being a resin or a rubber, the first addition member being adhered to the external surface of the weight member; and

a second addition member mounted on an external side of the first addition member while abutting an external surface of the first addition member, said second addition member being formed of a metal, with the specific gravity of said metal being greater than that of the first addition member and smaller than that of the weight member, the second addition member being exposed, the second addition member being adhered to the first addition member.

2. A golf club head comprising:

a head main body provided with a recessed part on the external surface thereof;

a weight member which is mounted in said recessed part and which is formed of a material having a specific gravity greater than that of the head main body, the weight member being made of an alloy;

a first addition member mounted on an external side of the weight member while abutting an external surface of said weight member, a base of said first addition member being a resin or a rubber, the first addition member being adhered to the external surface of the weight member, the first addition member being multiple-layered and including an adhesive layer and a resin layer; and

a second addition member mounted on an external side of the first addition member while abutting an external surface of the first addition member, with the specific gravity being greater than that of the first addition member and smaller than that of the weight member, the second addition member being exposed, the second addition member being adhered to the first addition member.

3. The golf club head of claim 2 , wherein the first addition member has a first adhesive layer on the weight member side, a second adhesive layer on the second addition member side, and a resin member disposed between the first adhesive layer and the second adhesive layer.

4. A golf club head comprising:

a head main body provided with a recessed part on the external surface thereof, a through hole being provided at a bottom face of the recessed part;

a weight member which is mounted in said recessed part and which is formed of a material having a specific gravity greater than that of the head main body, the weight member being made of an alloy, the weight member having a basal part and a projecting part protruding from the basal part, the through hole and the projecting part being engaged by a screw structure;

a first addition member mounted on an external side of the weight member while abutting an external surface of said weight member, a base of said first addition member being a resin or a rubber, the first addition member being adhered to the external surface of the weight member; and

a second addition member mounted on an external side of the first addition member while abutting an external surface of the first addition member, with the specific gravity being greater than that of the first addition member and smaller than that of the weight member, the second addition member being exposed, the second addition member being adhered to the first addition member.

5. A golf club head comprising:

a head main body provided with a recessed part on the external surface thereof;

a weight member which is mounted in said recessed part and which is formed of a material having a specific gravity greater than that of the head main body, the weight member being made of an alloy;

a first addition member mounted on an external side of the weight member while abutting an external surface of said weight member, a base of said first addition member being a resin or a rubber, the first addition member being adhered to the external surface of the weight member, the first addition member having a thickness T 1 , wherein 0.02 mm≦T 1 ≦4.5 mm; and

a second addition member mounted on an external side of the first addition member while abutting an external surface of the first addition member, with the specific gravity being greater than that of the first addition member and smaller than that of the weight member, the second addition member being exposed, the second addition member being adhered to the first addition member, the second addition member having a thickness T 2 , wherein 0.5 mm≦T 2 ≦2.5 mm.

6. A golf club head comprising:

a head main body provided with a recessed part on the external surface thereof;

a weight member which is mounted in said recessed part and which is formed of a material having a specific gravity greater than that of the head main body;

a first addition member mounted on an external side of the weight member while abutting an external surface of said weight member, a base of said first addition member being a resin or a rubber, the first addition member being adhered to the external surface of the weight member;

a second addition member mounted on an external side of the first addition member while abutting an external surface of the first addition member, said second addition member being formed of a metal, with the specific gravity of said metal being greater than that of the first addition member and smaller than that of the weight member, the second addition member being exposed, the second addition member being adhered to the first addition member; and

a covering layer provided on an external surface of the second addition member.

7. The golf club head of claim 6 , wherein the covering layer is a plated layer or a vapor deposited layer.