An optical signal receiving apparatus, able to detect a bit rate of a received signal by a low cost and able to change to a suitable reception band width corresponding to the received bit rate, provided with a bit rate detection circuit detecting a bit rate from a consumed current flowing through a CMOS inverter (CMOS-INV) connected to an output of a PIN photodiode converting an input optical signal to an electrical signal and a control circuit controlling a reverse bias voltage applied to a variable capacity diode provided at any location in the PIN photodiode or reception apparatus.