An electric cylinder includes: an outer cylinder including, on one end side, a fixing section; a rod configured to be capable of expanding and contracting in an axis direction from an opening on the one end side of the outer cylinder; a bearing provided on the other end side end and on the inside of the outer cylinder; a rotating shaft supported by the bearing and driven to rotate; a screw mechanism configured to convert a rotational motion of the rotating shaft into a linear motion of the rod and transmit the linear motion; and a distortion detecting unit provided on the outer circumference of the outer cylinder. The outer cylinder includes at least two or more division members that can be divided and combined. The distortion detecting unit is provided in one division member among the two or more division members.