A syringe cap includes a projecting part extending in the circumferential direction of the cap body； this projecting part includes an apex located radially outward of the cap body from the outer peripheral surface of the cap body, a first inclined surface having a starting edge at the apex as well as an ending edge on the outer peripheral surface of the cap body which is on the base end side of the cap body from the starting edge, and a second inclined surface having a starting edge at the apex as well as an ending edge on the outer peripheral surface of the cap body which is on the tip end side of the cap body from the starting edge； and the shortest distance from the starting edge to the ending edge of the first inclined surface is less than the shortest distance from the starting edge to the ending edge of the second inclined surface.
