Abstract: A water jet propulsion type outboard motor which includes: a power source; a driving system; a housing; a curved tubular duct member; guide blades; and an impeller. The duct member is fixed to the housing on which the power source is mounted, and having a suction port and a discharge port. The guide blades are provided within the duct member in the vicinity of the discharge port of the duct member. The impeller is rotated by the driving system for transmitting a driving power of the power source, and has a spiral blade with outer peripheral edge thereof close to an inner peripheral face of the duct member, and outer peripheral distal end portion thereof extending toward the suction port.