An electronic device comprises a housing, a battery retainer arranged in the housing, a battery, a movable member and at least one resilient member. The battery retainer defines a battery cavity and a spring tab. The battery retained in the battery cavity defines a recessed portion and a protrusion protruding from the bottom of the recessed portion. The recessed portion defines a plurality of sloped surfaces and vertical walls surrounding the protrusion. The protrusion defines a side wall. The movable member comprises a first end rotatably connected to the battery retainer and a second end connecting the sloped surfaces. After the battery is pushed into the battery cavity, one of the sloped surfaces engages the second end of the movable member to move until the second end disengages from the side wall of the protrusion.