A reverse input shutoff clutch, comprising: an input member; an output member coaxially arranged with the input member; a pressed member having a pressed surface; and an engaging element that, when a rotational torque is inputted to the input member, moves in a direction away from the pressed surface due to engagement with the input member, and by engaging with the output member, transmits the rotational torque that is inputted to the input member to the output member; and when a rotational torque is reversely inputted to the output member, moves in a direction toward the pressed surface due to engagement with the output member, and by coming in contact with the pressed surface, completely shuts off not to transmit the rotational torque that is reversely inputted to the output member, or transmits part of the rotational torque that is reversely inputted to the output member to the input member, and shuts off a remaining part of the rotational torque that is reversely inputted to the output member, wherein the pressed surface is an arc-shaped concave surface, and pressing surfaces that are pressed against the pressed surface are provided at two positions spaced apart in a circumferential direction of the engaging element, the pressing surfaces respectively being constructed by a cylindrical convex surface having a radius of curvature that is smaller than the radius of curvature of the pressed surface, characterized in that a cross-sectional shape of the pressed surface and a cross-sectional shape of the pressing surfaces of the engaging element pressed against the pressed surface are both arc shaped, and a radius of curvature of the cross-sectional shape of the pressing surfaces is made smaller than a radius of curvature of the cross-sectional shape of the pressed surface. an input member; an output member coaxially arranged with the input member; a pressed member having a pressed surface; and an engaging element that, when a rotational torque is inputted to the input member, moves in a direction away from the pressed surface due to engagement with the input member, and by engaging with the output member, transmits the rotational torque that is inputted to the input member to the output member; and when a rotational torque is reversely inputted to the output member, moves in a direction toward the pressed surface due to engagement with the output member, and by coming in contact with the pressed surface, completely shuts off not to transmit the rotational torque that is reversely inputted to the output member, or transmits part of the rotational torque that is reversely inputted to the output member to the input member, and shuts off a remaining part of the rotational torque that is reversely inputted to the output member, wherein the pressed surface is an arc-shaped concave surface, and pressing surfaces that are pressed against the pressed surface are provided at two positions spaced apart in a circumferential direction of the engaging element, the pressing surfaces respectively being constructed by a cylindrical convex surface having a radius of curvature that is smaller than the radius of curvature of the pressed surface, characterized in that a cross-sectional shape of the pressed surface and a cross-sectional shape of the pressing surfaces of the engaging element pressed against the pressed surface are both arc shaped, and a radius of curvature of the cross-sectional shape of the pressing surfaces is made smaller than a radius of curvature of the cross-sectional shape of the pressed surface.