A light receiving sensor (1) includes: a photodiode (PD) which generates a photocurrent (Ipd) upon receipt of light; a transistor (Tr11) through which the photocurrent (Ipd) flows; a transistor (Tr12) which forms, together with the transistor (Tr11), a first current mirror circuit (CM1); a transistor (Tr9) whose channel type is different from that of the transistor (Tr11), and a resistor (R10) which converts, to a voltage, a current flowing through the transistors (Tr11 and Tr12). The first current mirror circuit (CM1) amplifies the photocurrent (Ipd), the transistor (Tr11) has a source connected with a gate of a MOS transistor (Tr9), and the MOS transistor (Tr9) has a threshold voltage that is set to be equal to or above a threshold voltage of the transistor (Tr11). This decreases a capacity of the photodiode (PD) and therefore allows the light receiving sensor (1) to operate at a high speed while the photodiode (PD) is biased.