An imaging apparatus comprising: a light receiving element having a micro lens array provided with a plurality of micro lenses 111a arranged two-dimensionally, and a plurality of photoelectric conversion elements 112a provided for the plurality of micro lenses, and outputting a light receiving signal obtained by receiving a light beam from an optical system via the micro lens array; a detector 152 that detects a shift amount of image plane by the optical system for a plurality of focus detecting positions set at a plurality of positions in the image plane by the optical system; and a controller 160 that determines a focus adjusting range for the optical system based on the shift amount detected for each of the plurality of focus detecting positions, and obtains the light receiving signal at each of different positions within the focus adjusting range with the light receiving element.