A velocity detection apparatus comprising: a first light detector including a first emitter that illuminates optically identifiable marks disposed on a moving body, and a first light receiver that detects light from the optically identifiable marks; a second light detector including a second emitter that illuminates the optically identifiable marks and a second light receiver that detects light from the optically identifiable marks, wherein the second light detector is arranged at a predetermined interval from the first light detector in a moving direction of the moving body; and a velocity calculating unit that calculates a moving velocity of the moving body, characterized by a reference signal generating unit that generates a reference signal having a predetermined frequency; a time-sharing light emitting unit that allows the first emitter and the second emitter to emit light in a time-sharing manner in synchronism with the reference signal using an energization control unit that controls energization states of the first emitter and the second emitter; a sampling unit that samples outputs of the first light detector and the second light detector in synchronism with the reference signal; an identical point detecting unit that detects a first time at which the first light detector detects a first mark among the optically identifiable marks, and a second time different from the first time at which the second light detector detects the first mark through interpolating computation using the outputs of the first light detector and the second light detector sampled by the sampling unit; wherein the velocity calculating unit calculates the moving velocity of the moving body using the first time and the second time detected by the identical point detecting unit. a first light detector including a first emitter that illuminates optically identifiable marks disposed on a moving body, and a first light receiver that detects light from the optically identifiable marks; a second light detector including a second emitter that illuminates the optically identifiable marks and a second light receiver that detects light from the optically identifiable marks, wherein the second light detector is arranged at a predetermined interval from the first light detector in a moving direction of the moving body; and a velocity calculating unit that calculates a moving velocity of the moving body, characterized by a reference signal generating unit that generates a reference signal having a predetermined frequency; a time-sharing light emitting unit that allows the first emitter and the second emitter to emit light in a time-sharing manner in synchronism with the reference signal using an energization control unit that controls energization states of the first emitter and the second emitter; a sampling unit that samples outputs of the first light detector and the second light detector in synchronism with the reference signal; an identical point detecting unit that detects a first time at which the first light detector detects a first mark among the optically identifiable marks, and a second time different from the first time at which the second light detector detects the first mark through interpolating computation using the outputs of the first light detector and the second light detector sampled by the sampling unit; wherein the velocity calculating unit calculates the moving velocity of the moving body using the first time and the second time detected by the identical point detecting unit.