A remote control transmitter detects motion in a specific direction or in a rotational direction around a specific axis: The transmitter includes a battery placed on a bottom surface side within a case containing circuitry of the transmitter. The bottom surface side has a convex surface, with a center of curvature C coincident in the upward direction of the force of gravity above a center of gravity G of the transmitter. When placed on a flat surface, the transmitter assumes a stable orientation such that when the transmitter is grasped in order to perform a motion-based operation, it can be can be assumed that the vertical direction is the direction of the line joining the center of curvature C of the stable portion to the center of mass G, as an absolute direction for reference in detecting the motion operation.