To improve convenience in exchange work or the like by holding a cylinder lock in a casing of a game machine.

A cylinder holder 1 is for holding the cylinder lock for locking the casing when exchanging the cylinder lock in the state of being attached inside the casing of the game machine, and includes an attaching member 10 provided with an attaching surface for attaching the cylinder holder 1 inside the casing, a support member 20 extended in the direction of separating from the attaching surface in the attaching member 10, a cylindrical holding member 30 extended along the attaching surface from the front end side of the support member 20, and a maintaining member 40 arranged along a cylindrical inner peripheral surface in the holding member 30. The holding member 30 is capable of inserting the cylinder lock 200 to the cylindrical inner peripheral side through a slit 32 by turning respective parts in the direction of widening an opening width by the slit 32, and holding the cylinder lock 200 on the cylindrical inner peripheral side by turning the respective parts in the direction of narrowing the opening width by the slit 32.