An information acquisition method implemented by one or more processor, includes: acquiring, for each of frames, a brightness value corresponding to a position of a color filter from a light receiving device including light receiving elements whose light receiving surfaces are covered with color filters, the color filters including the color filter and the color filters comprising at least first color filters transmitting light of a wavelength band corresponding to a first color and second color filters transmitting light of a wavelength band corresponding to a second color; and acquiring information on a mobile device based on difference between brightness values of the position acquired from a plurality of frames and at least one of a threshold for the first color filters and a threshold for the second color filters.