An energy-saving heating and hot water supply system includes a main heat exchanger, a circulation pump, a hot water supply heat exchanger and a hot water distributor. The main heat exchanger produces heating water through a heat exchange. The circulation pump circulates the heating water produced in the main heat exchanger so that the heating water is supplied to and collected from each household or floor. The hot water supply heat exchanger produces hot water through a heat exchange between water for hot water supply and the heating water supplied from the main heat exchanger and circulates the produced hot water in a floor coil through the hot water distributor or directly circulates the produced hot water in the floor coil. The hot water distributor receives the heating water and circulates the received heating water in the floor coil provided for each household or floor.