Abstract: A button battery holder adapted to be inserted into an electronic equipment is disclosed. As the holder is mounted into the electronic equipment in the direction parallel to the electrode surfaces of the button battery, a battery holder insert hole and a battery holder mounting portion to be formed in the electronic equipment can be made small, thereby contributing to a reduction in size of the electronic equipment. Furthermore, if the orientation of the electrode surfaces is incorrect upon insertion of the button battery into the holder, the side peripheral portion of the button battery is caught by the opposite side portions of the button battery insert opening at the time of little insertion, and further insertion of the button battery is inhibited because the sectional shape of the button battery does not become coincident with the shape of the button battery insert hole under the incorrectly oriented condition of the button battery.