The low ultrasonic attenuation of fused quartz in the very high frequency range makes it attractive for an ultrasonic delay line. However, the temperature instability restricts its application. A method of stabilizing the delay time based on the properties of a positive temperature coefficient resistor that is used simultaneously as a temperature sensor and a regulator is discussed. This new type of temperature regulator improves the temperature coefficient of the delay time from 85 ppm/°C to 8 ppm/°C. A temperature‐stabilized wide‐band delay line has been fabricated for high definition television. A wide‐band frequency response is obtained by using LiNbO3transducers and new type bonding adhesion which is stiffened by irradiation of ultraviolet rays. The design of the delay line, which has a midband frequency of 45 MHz, a band width of 50 MHz, and a delay time of 29.55 ms, is presented and experimental results are also presented.