A shape detection method and device for detecting a shape of an object are disclosed. The device includes an ultrasonic wave transmission module, a reception module, an incoming direction detecting module, a propagation time detecting module, a front-surface reflection point detecting module, and a shape deriving module. The shape deriving module derives a shape of a front surface of the object using a plurality of the reflection points on the front surface of the object detected by the front-surface reflection point detecting module for a plurality of transducer groups.