A master input device operates a slave manipulator which includes joints corresponding to a plurality of degrees of freedom. The device includes an operating unit and detection units of two or more systems. The operating unit is capable of being changed in position and orientation by an operators operation. The operating unit is provided command values of a position and orientation of the slave manipulator as the position and orientation thereof change. The detection units individually detect different physical quantities related to the operating unit in order to detect the position and orientation of the operating unit.
