A medical manipulator including a drive unit, and a treatment tool (50, 50A, 50B) detachably mounted on the drive unit and configured to be driven by the drive unit, the medical manipulator comprising: an operation member connected to the treatment tool (50, 50A, 50B) and configured to drive so as to operate the treatment tool (50, 50A, 50B); a treatment tool side drive shaft configured to rotate about an axis thereof so as to drive the operation member; an operation amount detection member connected to the treatment tool (50, 50A, 50B); a treatment tool side detection shaft configured to rotate about an axis thereof in accordance with displacement of the operation amount detection member; a drive unit side drive shaft having a drive section configured to generate a driving force, the drive unit side drive shaft being installed at the drive unit, the drive unit side drive shaft being configured to be engaged with the treatment tool side drive shaft so as to transmit the driving force to the treatment tool side drive shaft; a drive unit side detection shaft having a detection section configured to detect a displacement amount of the operation amount detection member, the drive unit side detection shaft being installed at the drive unit, the drive unit side detection shaft being configured to be engaged with the treatment tool side detection shaft such that rotation of the treatment tool side detection shaft is transmitted to the drive unit side detection shaft; a shape regulation section (42, 42A, 91, 91A) having a detection unit (45,93) and being configured to regulate a shape of the treatment tool (50, 50A, 50B) to a predetermined shape by inserting the treatment tool (50, 50A, 50B); and a phase setting section configured to set phases in rotational directions of the treatment tool side drive shaft and the treatment tool side detection shaft, wherein the phase setting section sets the phases of the treatment tool side drive shaft and the treatment tool side detection shaft to correspond to a predetermined operation state when the phase setting section receives a signal from the detection unit (45, 93), the detection unit (45, 93) being configured to send the signal to the phase setting section when the treatment tool (50, 50A, 50B) is regulated as the predetermined operation state. an operation member connected to the treatment tool (50, 50A, 50B) and configured to drive so as to operate the treatment tool (50, 50A, 50B); a treatment tool side drive shaft configured to rotate about an axis thereof so as to drive the operation member; an operation amount detection member connected to the treatment tool (50, 50A, 50B); a treatment tool side detection shaft configured to rotate about an axis thereof in accordance with displacement of the operation amount detection member; a drive unit side drive shaft having a drive section configured to generate a driving force, the drive unit side drive shaft being installed at the drive unit, the drive unit side drive shaft being configured to be engaged with the treatment tool side drive shaft so as to transmit the driving force to the treatment tool side drive shaft; a drive unit side detection shaft having a detection section configured to detect a displacement amount of the operation amount detection member, the drive unit side detection shaft being installed at the drive unit, the drive unit side detection shaft being configured to be engaged with the treatment tool side detection shaft such that rotation of the treatment tool side detection shaft is transmitted to the drive unit side detection shaft; a shape regulation section (42, 42A, 91, 91A) having a detection unit (45,93) and being configured to regulate a shape of the treatment tool (50, 50A, 50B) to a predetermined shape by inserting the treatment tool (50, 50A, 50B); and a phase setting section configured to set phases in rotational directions of the treatment tool side drive shaft and the treatment tool side detection shaft, wherein the phase setting section sets the phases of the treatment tool side drive shaft and the treatment tool side detection shaft to correspond to a predetermined operation state when the phase setting section receives a signal from the detection unit (45, 93), the detection unit (45, 93) being configured to send the signal to the phase setting section when the treatment tool (50, 50A, 50B) is regulated as the predetermined operation state.