PURPOSE: To provide an optoelectronic integrated circuit which is capable of efficiently performing the self-learning in an optical neuro element by an optical signal.

CONSTITUTION: An optical input circuit 104 is composed by connecting a first hetero junction phototransistor 101 with a second hetero junction phototransistor 102 and a third hetero junction phototransistor 103. The first hetero junction phototransistor 101 is connected with a semiconductor laser 105, the second hetero junction phototransistor 102 is connected with a negative power source 106 and the third hetero junction phototransistor 103 is connected with a positive power source 107. Three sets of the optical input circuit 104 are connected with a semiconductor laser 105. By imparting learning light to the second or the third hetero junction phototransistor, the polarity of bias impressed on the first hetero junction transistor is changed. By changing the direction of current flowing in the optical input circuit, the self-learning by the optical signal can be realized.