A mechanism for detecting an amount of remaining sheets, includes: a sheet feeding tray to be accommodated in an apparatus main body such that the sheet feeding tray can be inserted into and withdrawn from the apparatus main body, in which sheets can be loaded in an inside of the sheet feeding tray; a tilting plate that is tiltably provided in the sheet feeding tray so as to tilt in accordance with an amount of remaining sheets in the sheet feeding tray; a rotating member that rotates between a starting end position and a final end position of rotation of the rotating member in association with the tilting of the tilting plate; and a locking mechanism that locks the rotation of the rotating member.