PROBLEM TO BE SOLVED: To provide a method for calculating a highly accurate sound related physical constant and temperature coefficient required for the design of a piezoelectric device, and a method for determining a crystal orientation and propagation direction optimal as the piezoelectric device by calculation using the method.SOLUTION: A highly accurate constant and temperature coefficient in a wide temperature range are obtained by calibrating the result of the temperature dependency of a sound velocity measured by a resonance method in a propagation mode coupled with piezo-electricity in a desired temperature range and measured by a pulse echo method in a propagation mode not coupled with the piezo-electricity on the basis of the result of highly accurate sound velocity measurement in the vicinity of the room temperature by an UMS technique. The crystal orientation and propagation direction optimal as the piezoelectric device are determined by a calculation using the obtained constant and temperature co
