A sheet cassette includes a tray main body part, and a tray expansion/contraction part supported by the tray main body part and configured to slide relative to the tray main body part to a cassette expanded position where the sheet cassette is in an expanded state and a cassette contracted position where the sheet cassette is in a contracted state. The tray expansion/contraction part includes a rear end regulation member configured to be moved in a direction in which recording media stacked in the sheet cassette are fed to regulate rear ends of the recording media and a sliding guide part configured to support the rear end regulation member to freely slide and forming a moving path of the rear end regulation member.