An automatic faucet comprising: a faucet main unit which includes a conduit pipe having a base end fixable to a support body and extending toward a user side, and a spout valve; a water pipe disposed inside the conduit pipe and supplying washing water to a spout port formed in a spout region as the distal end portion of the faucet main unit; a radio wave sensor operable to output a detection signal for sensing a user's behavior state; and control means operable, based on the detection signal from the radio wave sensor, to switch between open and closed states of the spout valve to thereby start and stop spouting of the washing water from the spout port, the automatic faucet further comprises: a radio wave propagation space defined between an inner peripheral surface of the conduit pipe and an outer peripheral surface of the water pipe so as to allow a radio wave to be propagated therethrough, wherein the radio wave sensor is provided in the faucet main unit at a position on the side of the base end, and set to emit a radio wave into the radio wave propagation space; a radio wave emitting port formed in the spout region to communicate with the radio wave propagation space so as to emit a radio wave propagated through the conduit pipe to the outside therethrough; characterised by directivity setting means for setting directivity of a radio wave to be emitted from the radio wave emitting port, the directivity setting means being configured to direct a radio wave being emitted from the radio wave emitting port, in such a manner that, during a water stopping state, the emitted radio wave lies along a spouting direction along which washing water is to be spouted from the spout port, and, during a water spouting state, a part of the radio wave emitted from the radio wave emitting port disposed offset toward the user side with respect to the spout port at least partially interferes with a user side-facing region of a peripheral surface of the stream of the spouted washing water. a faucet main unit which includes a conduit pipe having a base end fixable to a support body and extending toward a user side, and a spout valve; a water pipe disposed inside the conduit pipe and supplying washing water to a spout port formed in a spout region as the distal end portion of the faucet main unit; a radio wave sensor operable to output a detection signal for sensing a user's behavior state; and control means operable, based on the detection signal from the radio wave sensor, to switch between open and closed states of the spout valve to thereby start and stop spouting of the washing water from the spout port, the automatic faucet further comprises: a radio wave propagation space defined between an inner peripheral surface of the conduit pipe and an outer peripheral surface of the water pipe so as to allow a radio wave to be propagated therethrough, wherein the radio wave sensor is provided in the faucet main unit at a position on the side of the base end, and set to emit a radio wave into the radio wave propagation space; a radio wave emitting port formed in the spout region to communicate with the radio wave propagation space so as to emit a radio wave propagated through the conduit pipe to the outside therethrough; characterised by directivity setting means for setting directivity of a radio wave to be emitted from the radio wave emitting port, the directivity setting means being configured to direct a radio wave being emitted from the radio wave emitting port, in such a manner that, during a water stopping state, the emitted radio wave lies along a spouting direction along which washing water is to be spouted from the spout port, and, during a water spouting state, a part of the radio wave emitted from the radio wave emitting port disposed offset toward the user side with respect to the spout port at least partially interferes with a user side-facing region of a peripheral surface of the stream of the spouted washing water. a radio wave propagation space defined between an inner peripheral surface of the conduit pipe and an outer peripheral surface of the water pipe so as to allow a radio wave to be propagated therethrough, wherein the radio wave sensor is provided in the faucet main unit at a position on the side of the base end, and set to emit a radio wave into the radio wave propagation space; a radio wave emitting port formed in the spout region to communicate with the radio wave propagation space so as to emit a radio wave propagated through the conduit pipe to the outside therethrough; characterised by directivity setting means for setting directivity of a radio wave to be emitted from the radio wave emitting port, the directivity setting means being configured to direct a radio wave being emitted from the radio wave emitting port, in such a manner that, during a water stopping state, the emitted radio wave lies along a spouting direction along which washing water is to be spouted from the spout port, and, during a water spouting state, a part of the radio wave emitted from the radio wave emitting port disposed offset toward the user side with respect to the spout port at least partially interferes with a user side-facing region of a peripheral surface of the stream of the spouted washing water.