An electric cylinder system includes: a rod; a ball screw mechanism; a nut connected to the rod; a cylindrical body including a contact portion, the contact portion configured to be abutting the nut making the linear motion, the cylindrical body configured to support the ball screw mechanism in such a manner that the ball screw mechanism is displaceable in the axis direction of the ball screw; a strain detector fixed to the cylindrical body and configured to detect a value corresponding to a displacement of the ball screw mechanism; and a control section configured to make the ball screw mechanism be displaced by making the nut abut against the contact portion, and configured to detect an abnormality of the strain detector based on the value detected by the strain detector according to the displacement of the ball screw mechanism.