In this rod-less cylinder equipped with a guide mechanism (32), the guide mechanism (32) has: a first rail member (34), which is attached to the sidewall of a cylinder tube (2), has an inner rolling groove (34a), and is composed of alloyed steel; a second rail member (36), which is attached to a protrusion (31) of a slider (27), has an outer rolling groove (36a), and is composed of alloyed steel; a guide path (38a) provided in the protrusion of the slider and extending parallel to the second rail member; a connection member (39) having a connection path (39a) that connects the guide path and the inner rolling groove; and a plurality of rolling bodies (43) accommodated within an endless circulation path (42) formed of the inner rolling groove, the outer rolling groove, the guide path, and the connection path.