Abstract: A medical arm device to support a medical instrument has a tip part with a structure in which three rotation axes are disposed in order of a rotation axis around a longitudinal axis of the medical instrument, a yaw axis that rotates the medical instrument left and right with respect to a tip of a link, and a pitch axis that rotates the medical instrument up and down with respect to the tip of the link, and a first wire for rotation transmission of the yaw axis, a second wire for rotation transmission of the roll axis, a first rerouting pulley that reroutes the first wire between the pitch axis and the yaw axis, a second rerouting pulley that reroutes the second wire between the pitch axis and the yaw axis, and a third rerouting pulley that reroutes the second wire between the yaw axis and the roll axis.