A detection device includes: a movement detector that includes light emitters and light receivers, wherein in accordance with movement of a moving body among moving bodies, each corresponding to a different combination of a light emitter and a light receiver, a light reception level of the light receiver in a combination corresponding to the moving body changes; and a processor coupled to a memory storing instructions that, when executed by the processor, configure the processor to: cause each of the light emitters to sequentially emit light in each light emission period by providing a driving signal, and cause a signal level of the driving signal to differ between unit periods within the light emission period; and select, for each light emission period, a light reception level in one of the unit periods within the light emission period as a detected value for each of the light receivers.