A control unit causes a carriage to move in a width direction under a first movement control of changing a location of the carriage with a first resolution so that a sensor located forward in movement detects an edge of a medium. Thereafter, the first movement control is switched to a second movement control of changing the location of the carriage with a second resolution higher than the first resolution and the carriage is caused to move in the width direction so that a sensor located rearward in movement detects the edge.