To provide a battery lock mechanism which is not easily damaged, excellent in reliability and capable of miniaturization.

This battery lock mechanism 20 has a battery lock member 2 provided with a lock means for locking a battery 9 detachably with a recess 3a formed in a case 3, and a pushing means for biasing the battery 9 mounted on the recess 3a to the coming-off direction from the recess 3a. The lock means has a lock pawl 2a which is disposed upright on a main body of the battery 9 and can appear and disappear to a recess 10a formed in a protrusion 10 where the battery 9 can appear and disappear in the case 3 from an aperture formed in the case 3. The pushing means can be constituted to have a slope 2b for biasing the protrusion 10b of the battery 9 by swinging in the direction where the battery 9 comes off from the recess 3a of the case 3.