Golf club head

1. A hollow golf club head having an inner cavity and comprising

a face portion having a club face for hitting a ball, and

a perimeter region extending backwardly of the club head from the peripheral edge of the club face of the face portion so as to surround the face portion,

the perimeter region being provided with at least one set of a front part and a rear part, wherein the front part extends backward from the face portion and terminates to have a free rear end, and the rear part extends forward and terminates to have a free front end, wherein

the front part and the rear part are overlapped with each other without being fixed to each other so that, relatively to the rear part, the front part is movable in a front-back direction of the club head when hitting a ball, and

in the overlap between the front part and the rear part, the opposing surfaces of the front and rear parts closely contact each other so as to substantially close the inner cavity.

2. The golf club head according to claim 1 , wherein

the club head is composed of a first head member having an opening, and a second head member attached to the first member so as to close the opening,

the free rear end of said front part is formed by a part of an edge of the first head member surrounding the opening, and

the free front end of said rear part is formed by a front edge of the second head member.

3. The golf club head according to claim 2 , wherein

the first head member includes a sole portion of the club head forming a bottom surface of the club head,

said opening is formed in the sole portion, and

said front part is formed by a part of the sole portion between the face portion and the opening.

4. The golf club head according to claim 2 , wherein

the first head member is cup-shaped and comprises the face portion and a turnback extending backwardly of the club head to form said perimeter region,

the free rear end is formed by a part of the rear edge of the turnback,

the second head member is cup-shaped, and

said inner cavity of the golf club head is formed by an open cavity of the second head member and an open cavity of the first head member.

5. The golf club head according to claim 4 , wherein the turnback include a sole-side turnback provided with said free rear end.

6. The golf club head according to claim 1 , wherein the rear part comprises a front section and a rear section, the front section overlapping the front part on the inside of the front part and the rear section extending backwards from the front section so that the free rear end of the front part is not covered with the rear part from the outside of the front part.

7. The golf club head according to claim 6 , wherein the rear part is bent towards the inner cavity so that the front section thereof is positioned on the inside of the front part.

8. The golf club head according to claim 6 , wherein

a concave portion is formed behind the free rear end of the front part and on the outside of the rear part, and

an elastic material is disposed in the concave portion.

9. The golf club head according to claim 1 , wherein in a vertical cross section of the club head which includes the center of gravity of the club head and which is parallel to the front-back direction of the club head, the closely contacting opposing surfaces of the front part and the rear part are a circular arc whose center is positioned in a vicinity of a corner between the face portion and a crown portion of the club head.