An air spring includes an upper surface plate, a lower surface plate, and a diaphragm connecting the upper surface plate and the lower surface plate. The diaphragm has an annular shape having an opening on an inner circumferential side. In the diaphragm, an upper surface plate contact portion, which is a region defining the opening and being in contact with the upper surface plate, includes a deformed portion elastically deformed to protrude toward the lower surface plate side by contact with a support plate. The deformed portion is in contact with a sliding member located on the lower surface plate side when viewed from the deformed portion.