To realize a logarithmic amplifier circuit, whose temperature dependency is eliminated as much as possible.

A plurality of linear amplifiers A1, A2 and A3 are provided parallelly, an input signal is applied to these linear amplifiers A1, A2 and A3 and is also applied to a comparator 30 for performing level detection, and switching is performed so as to operate only one linear amplifier among the amplifiers in accordance with the level of the input signal.