Iron-type golf club head

1. An iron-type golf club head comprising:

a head body made of at least one kind of metallic material comprising a face member and a head body main portion, the head body having a face for hitting a golf ball and a recess portion, and

a weight member made of a metallic material having a specific gravity larger than said at least one kind of metallic material of the head body, the weight member fitted to and covering said recess portion to form a part of an outer surface of the golf club head,

wherein

said recess portion is formed on said head body main portion and defined by a first surface extending from said outer surface which is substantially parallel to said face and a second surface extending from said outer surface and intersecting with the first surface,

the weight member is welded to the first surface and the second surface so that a welded part between the weight member and the first surface extends along a part of the first surface from said outer surface of the golf club head to a first ending position, and a welded part between the weight member and the second surface extends along a part of the second surface from said outer surface of the golf club head to a second ending position,

the surface of the weight member opposed to said first surface and said second surface is provided at each of said first ending position and said second ending position with a step extending away from said first and said second surface to form a gap of at least 0.1 mm and at most 3.0 mm extending from the first ending position to the second ending position so as to form a closed space between said recess portion and said weight member,

said closed space is formed on a head bottom side of a sweet spot of said head,

said second surface intersects with the first surface at a right angle,

said gap is substantially constant from the first ending position to the second ending position and substantially same as the sizes of the steps, and

the closed space has a L-shaped cross-sectional shape.

2. The golf club head of claim 1 , wherein said recess portion has a volume of 0.05 to 1.5 cm 3 .

3. The golf club head of claim 1 , wherein a ratio S 2 /S 1 is from 0.15 to 0.70, wherein S 1 denotes a total area of facing surfaces between said recess portion and said weight member, and S 2 denotes the total area of surface of non-contact portions at which said recess portion and said weight member face each other through said closed space.

4. The golf club head of claim 1 , wherein said recess portion is provided on a back side of said head body.

5. The golf club head of claim 1 , wherein said recess portion is provided on a back side of said head body to extend along at least a sole of said head body.

6. The golf club head of claim 1 , wherein said closed space extends along said head body proximate to a sole of said head body and has a volume of 0.05 to 1.5 cm 3 .

7. The golf club head of claim 1 , wherein said closed space has a volume of 0.05 to 1.5 cm 3 .

8. The golf club head of claim 7 , wherein a ration S 2 /S 1 of a total area S 1 of the facing surfaces of said recess portion and said weight member which facing surfaces confront each other and a total area S 2 of non-contact portions of said facing surfaces which non-contact portions confront each other through said gap is in a range of from 0.15 to 0.70.