A medical manipulator comprising: an arm (20A-20C) formed in a tubular shape having a bending portion (32, 35) capable of bending; an insertion portion that is formed having channels, with the base end of the arm (20A-20C) being connected to the distal end of the insertion portion so that lumens (21A-21C) of the arm (20A-20C) and the channels are in communication; an operation portion (50, 60) for operating the bending portion (32, 35); and transmission members (22A-22D) that connect the bending portion (32, 35) and the operation portion (50, 60); wherein the operation portion (50, 60) comprises: an operation main body that supports the transmission members (22A-22D) so as to being capable of freely advancing and retreacting in the direction in which each of the transmission members (22A-22D) extend; a lever that has a tubular portion that allows insertion of a treatment tool (110, 120), with one end side of the tubular portion being coupled to each of the transmission members (22A-22D) via links (51A-51D), and the other end of the tubular portion capable of swinging about a rotation center that is established by the relative position with respect to the operation main body being fixed; and characterized by further comprising a guide member (43A, 43B) that is fixed to the operation main body and coupled to the lever, and that guides the lever so that the turning angle (θ2) about the rotation center at the other end of the lever is smaller than the turning angle (θ1) about the rotation center at the one end. an arm (20A-20C) formed in a tubular shape having a bending portion (32, 35) capable of bending; an insertion portion that is formed having channels, with the base end of the arm (20A-20C) being connected to the distal end of the insertion portion so that lumens (21A-21C) of the arm (20A-20C) and the channels are in communication; an operation portion (50, 60) for operating the bending portion (32, 35); and transmission members (22A-22D) that connect the bending portion (32, 35) and the operation portion (50, 60); the operation portion (50, 60) comprises: an operation main body that supports the transmission members (22A-22D) so as to being capable of freely advancing and retreacting in the direction in which each of the transmission members (22A-22D) extend; a lever that has a tubular portion that allows insertion of a treatment tool (110, 120), with one end side of the tubular portion being coupled to each of the transmission members (22A-22D) via links (51A-51D), and the other end of the tubular portion capable of swinging about a rotation center that is established by the relative position with respect to the operation main body being fixed; and characterized by further comprising a guide member (43A, 43B) that is fixed to the operation main body and coupled to the lever, and that guides the lever so that the turning angle (θ2) about the rotation center at the other end of the lever is smaller than the turning angle (θ1) about the rotation center at the one end. an operation main body that supports the transmission members (22A-22D) so as to being capable of freely advancing and retreacting in the direction in which each of the transmission members (22A-22D) extend; a lever that has a tubular portion that allows insertion of a treatment tool (110, 120), with one end side of the tubular portion being coupled to each of the transmission members (22A-22D) via links (51A-51D), and the other end of the tubular portion capable of swinging about a rotation center that is established by the relative position with respect to the operation main body being fixed; and characterized by further comprising a guide member (43A, 43B) that is fixed to the operation main body and coupled to the lever, and that guides the lever so that the turning angle (θ2) about the rotation center at the other end of the lever is smaller than the turning angle (θ1) about the rotation center at the one end.