A heat pump system comprising: a compressor configured to compress a refrigerant of an air conditioner; an engine configured to drive the compressor and comprising a suction unit and an exhaust unit, the suction unit being a suction manifold; a mixer configured to supply a mixed gas of a fuel and air towards the suction unit of the engine, the mixed gas being supplied to the suction manifold via a suction channel; a turbocharger comprising a turbine wheel connected to the exhaust unit of the engine and rotatable by an exhaust gas, and an impeller connected to the turbine wheel via a shaft and configured to compress the mixed gas; a supercharger connected with the turbocharger in parallel between the mixer and the suction unit of the engine; an intercooler configured to cool the mixed gas having passed at least one of the turbocharger and the supercharger; and an exhaust gas heat exchanger connected to a rear end of the turbine wheel in the exhaust suction of the engine, wherein the turbocharger is installed in a first passage branched from the mixer to a first side and having a first check valve installed therein, wherein the turbocharger is operating in a first engine rotation number range, wherein the supercharger is installed in a second passage branched from the mixer to a second side, which is opposite the first side, and having a second check valve installed therein, wherein the supercharger is operating in a second engine rotation number range which is smaller than the first engine rotation number range, wherein the heat pump system further comprises a third passage connected with the intercooler without passing the turbocharger and the supercharger from the mixer and having a third check valve installed therein, wherein the first passage and the second passage are combined to pass through the intercooler, wherein the suction channel is branched to be a branched channel having one end connected to the turbocharger and the other end connected to the supercharger, and wherein one end of the branched channel is connected to the first passage connected to the turbocharger and the other end of the branched channel is connected to the second passage connected to the supercharger such that the flow of the mixed gas is adjusted by using the first passage, the second passage and the third passage. a compressor configured to compress a refrigerant of an air conditioner; an engine configured to drive the compressor and comprising a suction unit and an exhaust unit, the suction unit being a suction manifold; a mixer configured to supply a mixed gas of a fuel and air towards the suction unit of the engine, the mixed gas being supplied to the suction manifold via a suction channel; a turbocharger comprising a turbine wheel connected to the exhaust unit of the engine and rotatable by an exhaust gas, and an impeller connected to the turbine wheel via a shaft and configured to compress the mixed gas; a supercharger connected with the turbocharger in parallel between the mixer and the suction unit of the engine; an intercooler configured to cool the mixed gas having passed at least one of the turbocharger and the supercharger; and an exhaust gas heat exchanger connected to a rear end of the turbine wheel in the exhaust suction of the engine, wherein the turbocharger is installed in a first passage branched from the mixer to a first side and having a first check valve installed therein, wherein the turbocharger is operating in a first engine rotation number range, wherein the supercharger is installed in a second passage branched from the mixer to a second side, which is opposite the first side, and having a second check valve installed therein, wherein the supercharger is operating in a second engine rotation number range which is smaller than the first engine rotation number range, wherein the heat pump system further comprises a third passage connected with the intercooler without passing the turbocharger and the supercharger from the mixer and having a third check valve installed therein, wherein the first passage and the second passage are combined to pass through the intercooler, wherein the suction channel is branched to be a branched channel having one end connected to the turbocharger and the other end connected to the supercharger, and wherein one end of the branched channel is connected to the first passage connected to the turbocharger and the other end of the branched channel is connected to the second passage connected to the supercharger such that the flow of the mixed gas is adjusted by using the first passage, the second passage and the third passage.