In this work, the change of sound wave speed by temperature is used in order to improve accuracy of ultrasonic distance measurement. Ambient temperature directly effects air density, thus air density effects sound wave speed. However most of ultrasonic distance measurement system assumes the sound speed is a constant. With this work, lower error rated system is suggested by considering adaptively changing soundwave speed according to ambient temperature. For the experimental work, a physical area is set and the ambient temperature is fluctuant changing, so several measurements performed with suggested and common way. In these conditions, highly sensitive sensors are used to measure ambient temperature and new soundwave speed is calculated for the temperature. When process repeated with new soundwave speed, it is observed that measurement accuracy is improved.