Provided is a cylinder device capable of preventing rotation unevenness while reducing power consumption and achieving compactification in particular. The present invention is to provide a cylinder device including a cylinder body and a shaft member supported in the cylinder body, the cylinder body being provided with a rotation port that communicates with an outer circumferential surface around the shaft member and rotates the shaft member based on a supply and discharge of a fluid. Thus, it is possible to prevent rotation unevenness while reducing power consumption and achieving compactification.