A stereoscopic imaging apparatus comprising a single photographic optical system; an image sensor, on which subject images that have passed through different first and second areas in a predetermined direction, respectively, are formed after being pupil-split, photoelectrically converting the subject images that have passed through the first and second areas, respectively, to output a first image and a second image; a diaphragm restricting a light flux incident on the image sensor; a subject information acquiring device acquiring distance information of a subject within a photographic angle of view or a device acquiring an amount of parallax of the subject; and a diaphragm control device controlling an F-number of the diaphragm so that a parallax between the first image and the second image is in a predetermined range based on the acquired distance information of the subject or the acquired amount of parallax of the subject.