A heating and hot water supply system that can reduce energy consumption is provided. The heating and hot water supply system includes a liquid heater for heating a liquid, a liquid-water heat exchanger, a room heater using heat of the liquid, a water-heating circuit in which the liquid is circulated between the liquid heater and the liquid-water heat exchanger, a room-heating circuit in which the liquid is circulated between the liquid heater and the room heater, a first valve for switching between the water-heating circuit and the room-heating circuit, a lower outward path for leading water from a lower part of a hot water storage tank to the liquid-water heat exchanger, the upper return path for leading the water from the liquid-water heat exchanger to an upper part of the hot water storage tank, a middle outward path for leading the water from a middle part of the hot water storage tank to the liquid-water heat exchanger, a middle return path for leading the water from the liquid-water heat exchanger to a middle part of the hot water storage tank, a second valve for switching between the lower outward path and the middle outward path, a third valve for switching between the upper return path and the middle return path, a middle hot water supply pipe connected to the middle part of the hot water storage tank, and an upper hot water supply pipe connected to the upper part of the hot water storage tank.