A laser tracking interferometer directs a laser beam to a retroreflector serving as an object to be measured to sense a displacement of the retroreflector using interference with a laser beam back reflected from the retroreflector. The laser tracking interferometer includes: a reference sphere; a carriage that rotates about a center of the reference sphere; a laser interferometer; a displacement gage for providing a displacement signal corresponding to a relative displacement between the reference sphere and the displacement gage; a data processing apparatus for computing a displacement of the retroreflector; a position sensitive detector for providing a position signal corresponding to deviation of a laser beam; and a controller for controlling rotation of the carriage based on the position signal so that the amount of deviation becomes zero.