A hybrid-type working machine comprising: an automotive vehicle body provided with a working mechanism in the front side; a counterweight that is provided in the rear side of said vehicle body to act as a weight balance to said working mechanism; an engine that is arranged in the front side of said counterweight and drives a hydraulic pump; an electric motor that is driven by said engine to generate power or assists in a drive of said engine by supply of power thereto; a heat exchanger for cooling a fluid including engine cooling water and/or hydraulic oil; a cooling fan for supplying cooling air to said heat exchanger; an electricity storage device that is arranged in a heat exchanger upstream room upstream of said heat exchanger in a flow direction of the cooling air supplied to said heat exchanger and stores power or discharges the power therein; and an inverter device for controlling an operation of said electric motor, characterized by: a radiator for electricity storage device that cools said electricity storage device; and a radiator for inverter that is provided aside from said radiator for electricity storage device to cool said inverter device, wherein said radiator for electricity storage device and said radiator for inverter are positioned between said heat exchanger and said electricity storage device in said heat exchanger upstream room, and are arranged in parallel in the flowing direction of said cooling air. an automotive vehicle body provided with a working mechanism in the front side; a counterweight that is provided in the rear side of said vehicle body to act as a weight balance to said working mechanism; an engine that is arranged in the front side of said counterweight and drives a hydraulic pump; an electric motor that is driven by said engine to generate power or assists in a drive of said engine by supply of power thereto; a heat exchanger for cooling a fluid including engine cooling water and/or hydraulic oil; a cooling fan for supplying cooling air to said heat exchanger; an electricity storage device that is arranged in a heat exchanger upstream room upstream of said heat exchanger in a flow direction of the cooling air supplied to said heat exchanger and stores power or discharges the power therein; and an inverter device for controlling an operation of said electric motor, characterized by: a radiator for electricity storage device that cools said electricity storage device; and a radiator for inverter that is provided aside from said radiator for electricity storage device to cool said inverter device, wherein said radiator for electricity storage device and said radiator for inverter are positioned between said heat exchanger and said electricity storage device in said heat exchanger upstream room, and are arranged in parallel in the flowing direction of said cooling air. a radiator for electricity storage device that cools said electricity storage device; and a radiator for inverter that is provided aside from said radiator for electricity storage device to cool said inverter device, wherein said radiator for electricity storage device and said radiator for inverter are positioned between said heat exchanger and said electricity storage device in said heat exchanger upstream room, and are arranged in parallel in the flowing direction of said cooling air.