According to the present invention, a method for predicting a bone mineral density using a bidirectional ultrasound transverse transmission technique comprises: a first ultrasonic wave emission step of receiving an electric signal from an ultrasonic conversion unit to allow a first transducer positioned on one side of a spongy bone to emit an ultrasonic wave to the spongy bone a first conversion step where a second transducer positioned on the other side of the spongy bone receives the ultrasonic wave transmitted through the spongy bone to transfer the ultrasonic wave to the ultrasonic conversion unit, and the ultrasonic conversion unit time-reverses a received ultrasonic signal to convert the ultrasonic signal a second ultrasonic wave emission step of transferring the ultrasonic signal converted by the ultrasonic conversion unit to the second transducer to allow the second transducer to emit the time-reversed ultrasonic signal to the spongy bone a second conversion step where the first transducer receives the ultrasonic signal emitted by the second transducer and transmitted through the spongy bone to transfer the ultrasonic signal to the ultrasonic conversion unit, and the ultrasonic conversion unit converts the received ultrasonic signal into an electric signal a measurement step where a measurement unit measures an ultrasonic attenuation coefficient from the electric signal converted by the ultrasonic conversion unit and a bone mineral density prediction step of transferring the ultrasonic attenuation coefficient measured by the measurement unit to a calculation unit, and allowing the calculation unit to perform linear regression analysis on the ultrasonic attenuation coefficient to predict a bone mineral density of the spongy bone. Accordingly, when predicting the bone mineral density of the spongy bone, an ultrasound wave is bidirectionally transmitted through the spongy bone such as a calcaneus using a new method to accurately predict the bone mineral density
