The light-emitting device includes: light-emitting elements linearly arrayed at intervals corresponding to a first resolution; switch elements electrically connected to the light-emitting elements; a transfer signal supply unit supplying a transfer signal for transmitting an on state among the switch elements by alternately repeating operations of turning on one switch element and turning on two adjacent switch elements including the one switch element; and a light-emission signal supply unit supplying a light-emission signal corresponding to a second resolution being a half of the first resolution, at supply timing changed according to whether in a first mode for causing an odd-numbered light-emitting element and a next even-numbered one to emit light as a pair, or the second mode for causing an even-numbered light-emitting element and a next odd-numbered one to emit light as a pair, the light-emitting elements arrayed at positions corresponding to the numbers.