A medical manipulator (10A to 10E) comprising: a surgical tool that has an end effector provided at a distal end and a handle in which at least one manual manipulation portion (24 and 26) is provided and is manipulable by a human hand, and in which the end effector is operated when a manipulating force of the manual manipulation portion (24 and 26) is mechanically transmitted; and a drive unit (14, 14a, 14b or 14c) that is detachable from the handle, wherein the drive unit (14, 14a, 14b or 14c) has unit-side manipulation portions (52 or 80a and 80b) that are manipulable by a human hand, and a driving source that is operated based on manipulation of the unit-side manipulation portions (52 or 80a and 80b), and in a state where the drive unit (14, 14a, 14b or 14c) is mounted on the handle, the end effector is operated by a drive of the driving source, wherein in addition to the manual manipulation portions (24 and 26), the handle has an opening and closing manipulation portion that mechanically transmits power by a manual manipulation thereof, and that opens and closes the end effector, wherein the surgical tool includes a posture changing mechanism that changes a posture of the end effector, wherein in a state where the drive unit (14, 14a, 14b or 14c) is mounted on the handle, the posture changing mechanism is operated under a driving operation of the driving source based on manipulation of the unit-side manipulation portions (52 or 80a and 80b), and in a state where the handle and the drive unit (14, 14a, 14b or 14c) are separated from each other, the posture changing mechanism is operated based on manipulation of the manual manipulation portions (24 and 26). a surgical tool that has an end effector provided at a distal end and a handle in which at least one manual manipulation portion (24 and 26) is provided and is manipulable by a human hand, and in which the end effector is operated when a manipulating force of the manual manipulation portion (24 and 26) is mechanically transmitted; and a drive unit (14, 14a, 14b or 14c) that is detachable from the handle, wherein the drive unit (14, 14a, 14b or 14c) has unit-side manipulation portions (52 or 80a and 80b) that are manipulable by a human hand, and a driving source that is operated based on manipulation of the unit-side manipulation portions (52 or 80a and 80b), and in a state where the drive unit (14, 14a, 14b or 14c) is mounted on the handle, the end effector is operated by a drive of the driving source, wherein in addition to the manual manipulation portions (24 and 26), the handle has an opening and closing manipulation portion that mechanically transmits power by a manual manipulation thereof, and that opens and closes the end effector, wherein the surgical tool includes a posture changing mechanism that changes a posture of the end effector, wherein in a state where the drive unit (14, 14a, 14b or 14c) is mounted on the handle, the posture changing mechanism is operated under a driving operation of the driving source based on manipulation of the unit-side manipulation portions (52 or 80a and 80b), and in a state where the handle and the drive unit (14, 14a, 14b or 14c) are separated from each other, the posture changing mechanism is operated based on manipulation of the manual manipulation portions (24 and 26).