1. An imaging method by which a relative positional relationship between a subject image formed on a solid-state imaging device and pixels in the solid-state imaging device is changed time-wise by an odd multiple of a half of an array pitch of the pixels so as to obtain a high-resolution image, the imaging method comprising: switching time-wise between a first time period for splitting a light beam from a subject into a plurality of light beams that have different polarization directions and then combining the plurality of light beams to form a single subject image on the solid-state imaging device and a second time period for splitting the light beam from the subject into the plurality of light beams that have different polarization directions and forming a plurality of subject images that overlap each other partially on the solid-state imaging device; obtaining a first image information on the single subject image based on pieces of signal information on the light beam reaching the pixels in the solid-state imaging device in the first time period; calculating a second image information on one of the plurality of subject images by using and computing pieces of signal information on the light beams reaching the pixels in the solid-state imaging device in the second time period; and using the first image information and the second image information to obtain a high-resolution image of the subject.