PURPOSE: To make the outputs of respective wavelengths uniform by amplifying the outputs of respective photodiode arrays in an ultraviolet region.

CONSTITUTION: Amplifiers 4, 4' are connected to each of the plural photodiodes 2A sensing wavelengths of an ultraviolet region among many photodiodes 2A, 2B of the same photodetection area arranged in such a way as to sense the prescribed wavelength from the ultraviolet region to a visible region. The output terminals of the amplifiers 4, 4' and the output terminals of the diodes 2B are connected to the output pins of a multiwavelength spectrophotometer via a selecting means, for example, a multiplexer 6 consisting of an MOS-FET. Thus the respective wavelength outputs including the ultraviolet region of low photodetecting sensitivity may be made uniform and the decrease in the resolution of wavelengths is prevented.