The envelope detector for detecting an envelope of a digital modulation signal in accordance with an embodiment of the present invention, includes: a mixer configured to receive the digital modulation signal and output a square signal squaring the digital modulation signal when being applied with bias voltage; a bias voltage applying unit configured to apply the bias voltage to the mixer; and a DC blocking capacitor configured to be connected to the mixer to block DC component included in the square signal. In accordance with the embodiment of the present invention, it is possible to provide the envelope detector having the simple structure while having the good receiving sensitivity and the wide dynamic range characteristics and detect the envelope of the modulated signal without transmitting the carrier signal in the transmitter and generating the separate signal in the receiver, thereby saving the costs consumed to implement the transceiver.