To provide such a push button locking device with specified push buttons to be pushed for unlocking as being capable of maintaining in a dead- locking condition as being in an unlocking condition.

Unlocking and non-unlocking push buttons 14A, 14B are provided on the surface of a holder case 7 to be set in and out. Unlocking and non- unlocking tumblers 15A, 15B, which are moved to the back in the face and back direction of the holder case 7 when the push buttons 14A, 14B are pushed, are provided in the holder case 7 in opposition to the push buttons 14A, 14B respectively. A slider 21 movable perpendicular to the moving direction of the tumblers 15A, 15B is provided in the holder case 7. By pushing only the several preset unlocking tumblers 15A with the push buttons 14A, the movement of the slider 21 being energized to a locking position to an unlocking position is allowed. For such a push button locking device, a dead-locking tumbler 15D to hold the slider 21 moved to an unlocking direction at an unlocking position and a dead-locking push button 14D to push the tumbler 15D are provided in the holder case 7.