A radiation photographing apparatus 1 includes a radiation irradiating unit 11, a first grating 31 which has a periodic structure which is formed by arranging a plurality of linear bodies 31b and forms a radiation image including a periodic intensity distribution by the passing radiation a detecting unit 14 which includes a radiation image detector 30 and acquire radiation image data by detecting the radiation image which is irradiated from the radiation irradiating unit to transmit the first grating and a subject and subjected to modulation for the periodic intensity distribution and a guide unit 70 which guides the arrangement of the subject in relation to an arrangement direction of a group of the linear bodies of the first grating.
