Battery holder and electric machine

A battery holder that retains a backup battery for an encoder of an electric machine driven by a servo motor and that is detachably fixed to an inner surface in an internal space of the electric machine, the internal space sealed by a cover configured for opening and closing an opening section of an outer wall of the electric machine, the battery holder comprising:

• a battery accommodation section that accommodates the battery and that allows the battery to be removed in a state in which the opening section is open;
• and
• a partition wall that is provided outside the battery accommodation section,
• wherein the partition wall blocks an access route that passes through the opening section and that reaches a component that is configured to be put into an active state by energization of the servo motor.