A light-emitting chip includes plural light-emitting thyristors having a first anode terminal, a first cathode terminal, and a first gate terminal, plural setting thyristors having a second anode terminal, a second cathode terminal, and a second gate terminal and setting the absolute value of a threshold voltage of each light-emitting thyristor to be smaller than that in an OFF state, plural transmission thyristors having a third anode terminal, a third cathode terminal, and a third gate terminal and setting the absolute value of a threshold voltage of each setting thyristor to be smaller than that in an OFF state, plural first connecting resistors connecting the first gate terminals and the second gate terminals, plural second connecting resistors connecting the second gate terminals and the third gate terminals, and plural third connecting resistors connecting the first gate terminals to a power supply line supplied with a source potential.