A position detection system includes: a contactor including a tracing unit that traces and fits with a recess or a protrusion of an object; a slide member; a sliding unit that causes the slide member to slide in two directions; a moving unit that causes the contactor to move in a direction perpendicular to a plane so as to cause the tracing unit of the contactor to trace and fit with the recess or the protrusion of the object; a contactor detecting unit that detects a position of the contactor in the plane; and an object position detecting unit that detects the position of the object based on movement amount of the contactor before and after the slide member slides on the sliding unit to slide, when the tracing unit traces the recess or the protrusion.