A liquid discharge apparatus comprising: a liquid discharge unit having a liquid discharge port, configured to discharge a liquid from the liquid discharge port toward an object, the liquid discharge unit being a carriage which is movable along at least one of a first axis and a second axis intersecting the first axis and movable along a third axis intersecting the first axis and the second axis, the third axis being parallel to a direction in which the liquid is discharged from the liquid discharge port toward the object; a contact detection unit attached to the carriage and including a first detector detachably attached to the carriage and a second detector detachably attached to the first detector; a position detector configured to detect a position of the liquid discharge unit relative to the object; circuitry configured to: calculate a movement trajectory of the liquid discharge unit based on the position of the liquid discharge unit relative to the object detected by the position detector; perform a first operation of causing the liquid discharge unit to move along the whole movement trajectory without discharging the liquid in order to detect obstacles; and perform a second operation of causing the liquid discharge unit to move along the movement trajectory while discharging the liquid to the object after the first operation; wherein the first detector includes detection plates (215a, 215b) on the front surface which are configured to detect an obstacle on the object, wherein the detection plates (215a, 215b) are configured to detect the obstacle on the object during the first operation, characterized in that a detection face of the detector for detecting the position of the carriage relative to the object is larger in area than the face of the liquid discharge port, wherein the position of the carriage relative to the object is measured by contact of the detection face with the object. a liquid discharge unit having a liquid discharge port, configured to discharge a liquid from the liquid discharge port toward an object, the liquid discharge unit being a carriage which is movable along at least one of a first axis and a second axis intersecting the first axis and movable along a third axis intersecting the first axis and the second axis, the third axis being parallel to a direction in which the liquid is discharged from the liquid discharge port toward the object; a contact detection unit attached to the carriage and including a first detector detachably attached to the carriage and a second detector detachably attached to the first detector; a position detector configured to detect a position of the liquid discharge unit relative to the object; circuitry configured to: calculate a movement trajectory of the liquid discharge unit based on the position of the liquid discharge unit relative to the object detected by the position detector; perform a first operation of causing the liquid discharge unit to move along the whole movement trajectory without discharging the liquid in order to detect obstacles; and perform a second operation of causing the liquid discharge unit to move along the movement trajectory while discharging the liquid to the object after the first operation; wherein the first detector includes detection plates (215a, 215b) on the calculate a movement trajectory of the liquid discharge unit based on the position of the liquid discharge unit relative to the object detected by the position detector; perform a first operation of causing the liquid discharge unit to move along the whole movement trajectory without discharging the liquid in order to detect obstacles; and perform a second operation of causing the liquid discharge unit to move along the movement trajectory while discharging the liquid to the object after the first operation; wherein the first detector includes detection plates (215a, 215b) on the front surface which are configured to detect an obstacle on the object, wherein the detection plates (215a, 215b) are configured to detect the obstacle on the object during the first operation, characterized in that a detection face of the detector for detecting the position of the carriage relative to the object is larger in area than the face of the liquid discharge port, wherein the position of the carriage relative to the object is measured by contact of the detection face with the object.