PROBLEM TO BE SOLVED: To provide an organic piezoelectric material having satisfactory durability in manufacturing processes and use environments and superior piezoelectric characteristics and constituting ultrasonic vibrators suitable for high frequencies/wide bands, to provide an ultrasonic vibrator that uses the organic piezoelectric material and a method of manufacturing the ultrasonic vibrator, and to provide an ultrasonic medical-use image diagnostic equipment.SOLUTION: The organic piezoelectric material 1 forms the ultrasonic vibrator 10. When an organic piezoelectric material, such as vinylidene fluoride, is left standing under an atmosphere within a temperature range of 50-70°C for 30 minutes, thermal shrinkage rate range lies in a range of -0.5 to +0.5%.
