Intraoral X-ray imaging auxiliary tool of the present invention (1), imaging media retention for holding (22) X-ray imaging medium for retaining the substrate to be inserted into the mouth (10), an imaging X-ray projection image The first distance is the distance between parts (20), tooth axis imaging object tooth and (20) the imaging medium holding portion (T) and (TX) detector for detecting a (L1) and (16) I include a.本発明の口腔内X線撮影補助具(1)は、口腔内に挿入される保定基板(10)と、X線投影像の撮像を行うX線像撮像媒体(22)を保持する撮像媒体保持部(20)と、撮像媒体保持部(20)と撮影対象歯牙(T)の歯軸(TX)との間の距離である第1距離(L1)を検出するための検出部(16)とを備える。
