A reverse input blocking clutch (1, 1a), comprising: a pressed member having a pressed surface on an inner circumferential surface thereof; an input member (2, 2a) having an input-side engaging portion (8, 8a) arranged on an inner side in a radial direction of the pressed surface, and being coaxially arranged with the pressed surface; an output member (3, 3a) having an output-side engaging portion (11, 11a) arranged further on the inner side in the radial direction than the input-side engaging portion (8, 8a) on the inner side in the radial direction of the pressed surface, and being coaxially arranged with the pressed surface; and an engaging element (5, 5a) having at least one pressing surface (32, 32a) facing the pressed surface, an input-side engaged portion (55, 64) configured to engage with the input-side engaging portion (8, 8a), and an output-side engaged portion (34, 34a) configured to engage with the output-side engaging portion (11, 11a), the engaging element (5, 5a) being arranged on the inner side in the radial direction of the pressed surface so as to be able to move in a first direction as a direction away from or toward the pressed surface; characterized in that an elastic member is arranged at a position that overlaps the output-side engaging portion (11, 11a) with respect to the first direction so as to be elastically stretched between the output-side engaging portion (11, 11a) and the engaging element (5, 5a); and the engaging element (5, 5a) is configured so that in a case where rotational torque is inputted to the input member (2, 2a), the engaging element (5, 5a) is moved away from the pressed surface due to engagement between the input-side engaging portion (8, 8a) and the input-side engaged portion (55, 64), the elastic member is elastically deformed so as to engage the output-side engaged portion (34, 34a) with the output-side engaging portion (11, 11a), and then the rotational torque inputted to the input member (2, 2a) is transmitted to the output member (3, 3a), and in a case where rotational torque is reversely inputted to the output member (3, 3a), the elastic member is elastically deformed so as to engage the output-side engaging portion (11, 11a) with the output-side engaged portion (34, 34a), the engaging element (5, 5a) is moved toward the pressed surface, and then the pressing surface (32, 32a) is pressed against the pressed surface so as to frictionally engage the pressing surface (32, 32a) with the pressed surface. a pressed member having a pressed surface on an inner circumferential surface thereof; an input member (2, 2a) having an input-side engaging portion (8, 8a) arranged on an inner side in a radial direction of the pressed surface, and being coaxially arranged with the pressed surface; an output member (3, 3a) having an output-side engaging portion (11, 11a) arranged further on the inner side in the radial direction than the input-side engaging portion (8, 8a) on the inner side in the radial direction of the pressed surface, and being coaxially arranged with the pressed surface; and an engaging element (5, 5a) having at least one pressing surface (32, 32a) facing the pressed surface, an input-side engaged portion (55, 64) configured to engage with the input-side engaging portion (8, 8a), and an output-side engaged portion (34, 34a) configured to engage with the output-side engaging portion (11, 11a), the engaging element (5, 5a) being arranged on the inner side in the radial direction of the pressed surface so as to be able to move in a first direction as a direction away from or toward the pressed surface; characterized in that an elastic member is arranged at a position that overlaps the output-side engaging portion (11, 11a) with respect to the first direction so as to be elastically stretched between the output-side engaging portion (11, 11a) and the engaging element (5, 5a); and the engaging element (5, 5a) is configured so that in a case where rotational torque is inputted to the input member (2, 2a), the engaging element (5, 5a) is moved away from the pressed surface due to engagement between the input-side engaging portion (8, 8a) and the input-side engaged portion (55, 64), the elastic member is elastically deformed so as to engage the output-side engaged portion (34, 34a) with the output-side engaging portion (11, 11a), and then the rotational torque inputted to the input member (2, 2a) is transmitted to the output member (3, 3a), and in a case where rotational torque is reversely inputted to the output member (3, 3a), the elastic member is elastically deformed so as to engage the output-side engaging portion (11, 11a) with the output-side engaged portion (34, 34a), the engaging element (5, 5a) is moved toward the pressed surface, and then the pressing surface (32, 32a) is pressed against the pressed surface so as to frictionally engage the pressing surface (32, 32a) with the pressed surface.