A male joint includes a male joint main body and a valve element provided coaxially with a central axis of the male joint main body. The valve element includes a shaft portion and a valve portion coaxially provided at a tip end of the shaft portion. The valve portion has a first surface intersecting with the central axis and a second surface that is connected to an outer edge of the first surface and extends along the central axis from the first surface to a base end at a base end portion. The valve portion further comprising a groove having an annular shape centered on the central axis at a side portion and a deformation portion on a base end side of the groove.