To provide an interior inspection structure of a golf club head that improves the convenience of inspection work by the ability to quickly inspect the quality of welding in the interior of a head body by the eye or an instrument, maintains a prescribed distance between the outer die and the inner die and maintains the balance of die flow.

The interior inspection structure is formed of the head body and at least two inspection holes. The head body can be joined with a face plate by welding. The inspection holes are installed in corresponding positions on the different sides of the head body and provides a maximum inspection range. When a light source provides illumination entering the interior of the head body via one inspection hole, the quality of welding in a welding path in the interior of the head body from the other visual inspection hole can be quickly detected.