The pitch and direction of sand ripples which are formed on the sea bottom are closely related to the direction and quantity of sand drift. A new measuring technique for the sand ripples is presented. In this measuring technique, a circular transducer array is located in the sand under the sea bottom, and an ultrasonic pulse which has a wide beam in the vertical plane is transmitted toward the sand ripples on the sea bottom surface. A transducer array was constructed and an experiment was performed in a water tank. Experimental results show that the pitch and direction of the sand ripples can be determined with satisfactory accuracy using this measuring thechnique.