There is provided an endoscope and a treatment tool-standing mechanism that allows a distal-end-portion body to be reduced in size while ensuring good operability of a standing base. In a distal-end-portion body of an endoscope, a standing lever is connected to a standing base through a rotating shaft, and the standing base is rotated by the rotation of the standing lever about the rotating shaft that is caused by the push and pull of an operation wire. The standing lever includes a first arm portion that extends from the rotating shaft and a second arm portion that extends in a direction different from the direction of the first arm portion, and a useless space formed on the proximal end side of the distal-end-portion body is reduced depending on the shape of the standing lever.