A radiation detection element includes a plurality of pixel electrodes, each pixel electrodes including a first electrode placed on the first surface of an insulating member and having an opening portion and a second electrode placed at the opening portion of the first electrode. The plurality of pixel electrodes is arrayed in the row direction and the column direction. The pitch of the pixel electrodes in the row direction and the column direction is 380 μm or less. An area ratio between the first electrode and the second electrode falls within the range of 14.5:1 to 154.6:1.