Illumination light supplied from an illumination light supplying unit that can selectively supply a plurality kinds of illumination lights whose wavelengths fall in different regions is supplied to an object. A signal picking up an image of the object is received by a programmable circuit unit that is programmably constructed based on circuit data, and then subjected to signal processing. A circuit data holding unit holds a plurality kinds of circuit data to be used for the programmable circuit unit. A control unit selects circuit data, which is used for the programmable circuit unit, from among all the circuit data items held in the circuit data holding unit corresponding to illumination light supplied from the illumination light supplying unit.