To enable further downsizing of an electronic apparatus with due consideration of arrangement and a structure of its battery lock mechanism.

A battery mounting part for mounting a battery in free detachment is provided on one face of a case of the electronic apparatus, and at the same time, a lock mechanism for locking the battery is provided on an adjoining face of the battery mounting part of the case. The lock mechanism consists of a lock slider plate biased in one direction to get engaged with and locked to the battery, and a slide button fitted through the slider plate and a turning lever and moving the lock slider plate in another direction to take off the battery, the slide button and the lock slider plate sliding on the surface or rear face of the adjoining face.