Disclosed is a method of acquiring physical information that acquires physical information by using a semiconductor device. The semiconductor device includes unit elements, each of which has a detecting unit and a unit signal generating unit. The method includes the steps of: providing an operation current supply unit supplying an operation current such that the unit signal generating unit outputs a unit signal, and a signal processing unit receiving the unit signal output from each of the unit elements forming the semiconductor device and outputting an output unit signal; and when a selective read mode is designated for reading the unit signal from a portion of the respective unit elements, an operation current of the output signal line of the unit signal generating unit not to be read is reduced so as to be smaller than an operation current of the output signal line of the unit signal generating unit to be read.