Outboard motor with internal combustion engine

An outboard motor includes an internal combustion engine (2) provided with a pair of intake valves (33a, 33b). The opening and closing operation of one of the intake valves (33a, 33b) can be paused. The internal combustion engine (2) comprises a vertical crankshaft (24), a cylinder head provided with an intake port (31) having a pair of intake openings (31U, 31L) for one combustion chamber, and a fuel injection valve (FP for injecting the fuel into the intake port (31). The intake port (31) has an upper branch section (31a) and a lower branch section (31b) extended under the upper branch section (31a). A valve train (M1) includes a valve-operation mode changing mechanism (M2). The valve-operation mode changing mechanism (M2) pauses the opening and closing operation of the first intake valve (33a) and operates the second intake valve (33b) for opening and closing the lower intake opening (31L) of the lower branch section (31b) while the internal combustion engine (2) is operating at engine speeds in a low-speed range. Thus, the amount of the stagnant fuel staying on the wall surface of the intake port (31) can be reduced, the variation of the air-fuel ratio can be suppressed, and the stability of combustion can be improved.