To provide a lock device for game machines made thinner for a larger room in the formation of a space for arraying the internal construction of the game machine and the game board.

The lock device has the first slide member 50 with a hook part 52 for the outer frame to be engaged with the outer frame, the second slide member 60 with a hook part 62 for the front door to be engaged with the front door, slide member support parts 71 for slidably supporting the first and second slide members 50 and 60 respectively and a cylinder lock mounting part 72 which has a cylinder lock 80 for sliding the first and second slid members 50 and 60 securely arrayed. A base plate 70 to be mounted at a prescribed location of the inner frame is also provided and the first and second members 50 and 60 are arranged side by side with the support surfaces 71a of the respective slide member support parts 71.