Provided is a line head including: a light emitting device array in which N (N is an integer of 2 or more) light emitting device groups including a plurality of light emitting devices is arranged; an output unit which sequentially outputs driving signals for driving the light emitting devices of the light emitting device groups to the light emitting device groups; and a delay unit which delays input timings when the driving signals output from the output unit are input to the light emitting devices, wherein the delay unit delays the input timings of the 1 to (N−1)th driving signals output from the output unit to the input timings of the Nth driving signals output from the output unit, and allows the light emitting devices of the different light emitting device groups simultaneously to emit light.