An outboard motor comprising: an engine including a crankshaft; a generator connected to the crankshaft and configured to generate power by driving of the engine; a driving force transmitter connected to the crankshaft and configured to transmit a driving force from the engine; a propeller shaft including a clutch and configured to rotate by switching from a neutral state of the outboard motor in which the clutch is disconnected from the driving force transmitter of the engine at idle to a non-neutral state of the outboard motor in which the clutch is connected to the driving force transmitter; and a controller configured or programmed to perform a control to reduce a rotation speed of the engine by regeneration of the generator based on a user's switching operation on a shift operator to switch the outboard motor from the neutral state to the non-neutral state, and then connect the clutch to the driving force transmitter while rotating the engine, wherein the outboard motor further comprises: a rotation speed sensor configured to detect the rotation speed of the engine, wherein the controller is configured or programmed to stop the control to reduce the rotation speed of the engine by the regeneration of the generator based on the rotation speed sensor detecting that the rotation speed of the engine has become equal to or lower than a first rotation speed wherein the generator is configured to drive the engine by power running in addition to power generation; and the controller is configured or programmed to perform a control to maintain the rotation speed of the engine at the first rotation speed or higher by the power running of the generator until the outboard motor is switched from the neutral state to at least the non-neutral state due to the clutch based on the rotation speed sensor detecting that the rotation speed of the engine has become equal to or lower than the first rotation speed. an engine including a crankshaft; a generator connected to the crankshaft and configured to generate power by driving of the engine; a driving force transmitter connected to the crankshaft and configured to transmit a driving force from the engine; a propeller shaft including a clutch and configured to rotate by switching from a neutral state of the outboard motor in which the clutch is disconnected from the driving force transmitter of the engine at idle to a non-neutral state of the outboard motor in which the clutch is connected to the driving force transmitter; and a controller configured or programmed to perform a control to reduce a rotation speed of the engine by regeneration of the generator based on a user's switching operation on a shift operator to switch the outboard motor from the neutral state to the non-neutral state, and then connect the clutch to the driving force transmitter while rotating the engine, wherein the outboard motor further comprises: a rotation speed sensor configured to detect the rotation speed of the engine, wherein the controller is configured or programmed to stop the control to reduce the rotation speed of the engine by the regeneration of the generator based on the rotation speed sensor detecting that the rotation speed of the engine has become equal to or lower than a first rotation speed wherein the generator is configured to drive the engine by power running in addition to power generation; and the controller is configured or programmed to perform a control to maintain the rotation speed of the engine at the first rotation speed or higher by the power running of the generator until the outboard motor is switched from the neutral state to at least the non-neutral state due to the clutch based on the rotation speed sensor detecting that the rotation speed of the engine has become equal to or lower than the first rotation speed. a rotation speed sensor configured to detect the rotation speed of the engine, wherein the controller is configured or programmed to stop the control to reduce the rotation speed of the engine by the regeneration of the generator based on the rotation speed sensor detecting that the rotation speed of the engine has become equal to or lower than a first rotation speed wherein the generator is configured to drive the engine by power running in addition to power generation; and the controller is configured or programmed to perform a control to maintain the rotation speed of the engine at the first rotation speed or higher by the power running of the generator until the outboard motor is switched from the neutral state to at least the non-neutral state due to the clutch based on the rotation speed sensor detecting that the rotation speed of the engine has become equal to or lower than the first rotation speed.