| 摘要 |
A head 2 includes a head body h1 and a neck part n1. The head body h1 and the neck part n1 are joined. The head body h1 has a body side joint surface s1 and a first recessed part opened in the body side joint surface s1. A space v1 is formed by the first recessed part r1. The neck part n1 has a neck side joint surface brought into surface contact with the body side joint surface s1 and a shaft hole 14. An abutted boundary surface Pt passes through a vicinity ad1 of a head height lowest point. When a plane perpendicular to an axis line z of the shaft hole 14 is defined as PL, and an angle between the plane PL and the abutted boundary surface Pt is theta degree, the angle theta is a plus value.
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