An engine system including an engine, an electric compressor including a first compressor which is provided in an intake flow path through which intake air supplied to the engine flows and is driven to compress the intake air, and an electric motor which drives the first compressor, a turbocharger including a second compressor which is provided in the intake flow path independently of the first compressor and compresses the intake air, and a turbine which is provided in an exhaust flow path through which exhaust air from the engine flows and is rotated by the exhaust air so as to drive the second compressor, a bypass flow path which is configured to bypass the first compressor and to connect an upstream side of the first compressor and an upstream side of the second compressor in the intake flow path, a bypass valve which opens or closes the bypass flow path, and a control device comprising a first acquisition unit which acquires an outlet pressure of the first compressor, characterized by the control device further comprising: a load determination unit which determines whether or not a load required by the engine exceeds a load threshold value; an electric motor control unit which starts the electric motor in a case where the required load exceeds the load threshold value; and a valve control unit which controls an opening degree of the bypass valve so as to increase with increasing required load in a case where the required load is equal to or less than the load threshold value and switches the bypass valve from an open state to a closed state in a case that the outlet pressure of the first compressor exceeds a first predetermined threshold value. an engine, an electric compressor including a first compressor which is provided in an intake flow path through which intake air supplied to the engine flows and is driven to compress the intake air, and an electric motor which drives the first compressor, a turbocharger including a second compressor which is provided in the intake flow path independently of the first compressor and compresses the intake air, and a turbine which is provided in an exhaust flow path through which exhaust air from the engine flows and is rotated by the exhaust air so as to drive the second compressor, a bypass flow path which is configured to bypass the first compressor and to connect an upstream side of the first compressor and an upstream side of the second compressor in the intake flow path, a bypass valve which opens or closes the bypass flow path, and a control device comprising a first acquisition unit which acquires an outlet pressure of the first compressor, characterized by the control device further comprising: a load determination unit which determines whether or not a load required by the engine exceeds a load threshold value; an electric motor control unit which starts the electric motor in a case where the required load exceeds the load threshold value; and a valve control unit which controls an opening degree of the bypass valve so as to increase with increasing required load in a case where the required load is equal to or less than the load threshold value and switches the bypass valve from an open state to a closed state in a case that the outlet pressure of the first compressor exceeds a first predetermined threshold value. a load determination unit which determines whether or not a load required by the engine exceeds a load threshold value; an electric motor control unit which starts the electric motor in a case where the required load exceeds the load threshold value; and a valve control unit which controls an opening degree of the bypass valve so as to increase with increasing required load in a case where the required load is equal to or less than the load threshold value and switches the bypass valve from an open state to a closed state in a case that the outlet pressure of the first compressor exceeds a first predetermined threshold value.