A radiation imaging apparatus is provided. The radiation imaging apparatus includes a radiation source configured to emit radiation from a first focal point, a plurality of radiation detecting elements disposed opposite to the radiation source and arranged in a channel direction, a plurality of collimator plates provided along the channel direction so as to separate the radiation detecting elements, the collimator plates including radiation absorption members at surfaces of at least one first collimator plate located on a first end side and at least one second collimator plate located on a second end side such that radiation shielding effects of the first and second collimator plates become substantially equivalent when the surfaces of the first and second collimator plates are located along a radial direction from a second focal point, and a data acquisition unit configured to acquire radiation projection data from the radiation detecting elements.