A hybrid-type construction machine that includes an engine, a hydraulic pump driven by the engine, a swing body, an electric motor for driving the swing body, a hydraulic motor driven by the hydraulic pump for driving the swing body, a controller having a hydraulic electric combined swing controlling block that is configured to control the swing body to be swung by simultaneous drive by the electric motor and the hydraulic motor and having an electric alone swing controlling block that is configured to control the swing body to be swung by the electric motor alone, a swing operation lever apparatus configured to issue an instruction for driving the swing body; and an operation amount detection unit (74c, 74d) configured to detect an operation amount of the swing operation lever apparatus characterized in that the hybrid-type construction machine comprises a work mode changeover unit (77; 110; 120) by which an operator changes over a work mode, the work mode being prepared as a plurality of work modes in accordance with an aspect of a work, whether or not the electric alone swing controlling block is to be used being set for each of the work modes, and the controller is configured to control the swing body to be swung by the electric alone swing controlling block when a work mode in which position accuracy is demanded is selected by the work mode changeover unit (77; 110; 120), and wherein the electric alone swing controlling block of the controller is configured to: fetch an operation amount of the swing operation lever apparatus detected by the operation amount detection unit (74c, 74d); and control output power of the electric motor by setting, in a region in which the operation amount is small, output power equal to that in combined driving of the electric motor and the hydraulic motor as a target value, and setting, when the operation amount is a maximum value, output power that does not exceed a limit output power of the electric motor as a target value. a hydraulic pump driven by the engine, a swing body, an electric motor for driving the swing body, a hydraulic motor driven by the hydraulic pump for driving the swing body, a controller having a hydraulic electric combined swing controlling block that is configured to control the swing body to be swung by simultaneous drive by the electric motor and the hydraulic motor and having an electric alone swing controlling block that is configured to control the swing body to be swung by the electric motor alone, a swing operation lever apparatus configured to issue an instruction for driving the swing body; and an operation amount detection unit (74c, 74d) configured to detect an operation amount of the swing operation lever apparatus characterized in that the hybrid-type construction machine comprises a work mode changeover unit (77; 110; 120) by which an operator changes over a work mode, the work mode being prepared as a plurality of work modes in accordance with an aspect of a work, whether or not the electric alone swing controlling block is to be used being set for each of the work modes, and the controller is configured to control the swing body to be swung by the electric alone swing controlling block when a work mode in which position accuracy is demanded is selected by the work mode changeover unit (77; 110; 120), and wherein the electric alone swing controlling block of the controller is configured to: fetch an operation amount of the swing operation lever apparatus detected by the operation amount detection unit (74c, 74d); and control output power of the electric motor by setting, in a region in which the operation amount is small, output power equal to that in combined driving of the electric motor and the hydraulic motor as a target value, and setting, when the operation amount is a maximum value, output power that does not exceed a limit output power of the electric motor as a target value. fetch an operation amount of the swing operation lever apparatus detected by the operation amount detection unit (74c, 74d); and control output power of the electric motor by setting, in a region in which the operation amount is small, output power equal to that in combined driving of the electric motor and the hydraulic motor as a target value, and setting, when the operation amount is a maximum value, output power that does not exceed a limit output power of the electric motor as a target value.