This paper discusses ultrasonic measurements of three dimensional (3 D) coordinate. Two methods are introduced in which two or three different ultrasonic waves are used. From a moving transmitter, waves are sent intermittently to eliminate influence of reflected waves and received by some fixed receivers. Phase differences are measured between the transmitted and received waves to calculate the distances between the transmitter and receivers. Then 3D coordinates are calculated by triangulation. The first method uses three kinds of waves and 3 D coordinates are determined only from the measured phase shifts. In the second one, the phase shifts of two waves and propagation time of one wave are used. Some experiments are made in a space of 300 mm×300 mm×1000 mm. By the first and second methods, errors of 1 D measurements are less than 0.1 mm and those of 3 D measurements are less than 1 mm.