Provided is an ultrasonic sensor device and a sensing method thereof. The device includes a driving unit for providing a transmission pulse to a transducer which transmits an ultrasonic wave and receives an echo of the ultrasonic wave; an amplifier for amplifying an electrical signal for the echo; an analog-to-digital converter for converting the amplified electrical signal into an original digital signal; a signal processor for performing an envelope extraction processing of the original digital signal to generate an extracted signal; and a control unit for outputting a distance signal with respect to an external object based on the original digital signal and the extracted signal, wherein the control unit includes: a test frequency generator for applying a test frequency signal to the transducer, and an excitation frequency measuring unit for measuring the excitation frequency generated in the transducer.