The invention provides a circuit device, embedded in an object, which includes a plurality of light-emitting devices, a motion-actuated switch, a controller and a selector. The motion-actuated switch senses a first motion of the object and generates a first controlling signal. The controller selectively drives the plurality of light-emitting devices to emit lights in a first period in a first sequence and a first flashing frequency according to the first controlling signal. After the first period, the motion-actuated switch senses a second motion of the object and generates a second controlling signal. The controller selectively drives the plurality of light-emitting devices to emit lights in a second period in the first sequence and a second flashing frequency according to the second controlling signal. The selector generates a selecting signal and the controller selectively controls the number of lighting light-emitting devices according to the selecting signal.