To configure a light emitting quantity control circuit without the use of an operational amplifier in the image reader.

The image reader is provided with a light emitting element whose light emitting quantity is changed in response to a conduction current, a light emitting diode array 21 that emits a read original, a photoelectric conversion means that receives a reflected light from the read original receiving the light emitted by the light emitting diode array 21 and provides an output of a read signal in response to a light receiving amount, and a conduction current control means that provides an output of a conduction current control voltage to control the conduction current through the light emitting element, and bipolar transistors(TRs) TR1, TR2 of Darlington connection to vary the conduction current of the light emitting element in response to the conduction current control voltage in which a base of the bipolar TR1 1 is connected to an output terminal of the conduction current control means.