A receiver and transmitter chips packaging structure and an automotive radar detector device using same are disclosed. The receiver/transmitter chips packaging structure includes a redistribution layer, a chip set and a molded encapsulation layer. The chip set includes a receiver chip, a transmitter chip and a radio-frequency (RF) processing chip arranged on one side of redistribution layer. The molded encapsulation layer covers the side of the redistribution layer having the receiver, transmitter and RF processing chips arranged thereon and accordingly, enclosed the chip set therein. And, the RF processing chip is electrically connected to the receiver chip and the transmitter chip via a plurality of conductive lines embedded in the redistribution layer.