A vessel propulsion apparatus comprising: an engine having a crankshaft, the engine being configured to rotate the said crankshaft in a forward rotation direction; a rotation speed detector (25, 74) configured to detects a rotation speed of the crankshaft; a propeller shaft configured to be coupled to a propeller; a shift switch arranged to switch between a engaged state in which rotation of the crankshaft is transmitted to the propeller shaft and a neutral state in which transmission of rotation between the crankshaft and the propeller shaft is blocked; a shift state detector configured to detect which of the engaged state and the neutral state the shift switch is in; an intake passage configured to supply air to a combustion chamber of the engine; a throttle valve that is provided in the intake passage and is configured to adjust an air volume to be supplied to the combustion chamber; an intake pressure sensor configured to detect an intake pressure inside the intake passage; and a control unit configured to receive inputs of detection values from the rotation speed detector (25, 74), the shift state detector and the intake pressure sensor, and is configured or programmed to determine that the crankshaft is reversely rotated in a direction opposite to the forward rotation direction by an external force input from the propeller shaft when a predetermined reverse rotation recording condition is satisfied, and that stores reverse rotation information, characterized in that the intake pressure sensor is configured to detect an intake pressure inside the intake passage wherein the said intake pressure sensor is disposed between the throttle valve and the combustion chamber, wherein the said predetermined reverse rotation recording condition includes a first condition that an intake pressure after the shift switch switches from the neutral state to the engaged state while the crankshaft rotates in the forward rotation direction is larger than a first value equal to or higher than an atmospheric pressure, wherein the control unit is configured or programmed to perform misfire control of the engine when it is determined that the crankshaft is reversely rotating, wherein the said determination that the crankshaft is reversely rotating is based on a pulse output corresponding to rotation of the crankshaft, and the control unit is configured or programmed to store the reverse rotation information when the said predetermined reverse rotation recording condition is satisfied after the said misfire control is performed in accordance with the said determination that the crankshaft is reversely rotating based on the pulse output corresponding to rotation of the crankshaft. an engine having a crankshaft, the engine being configured to rotate the said crankshaft in a forward rotation direction; a rotation speed detector (25, 74) configured to detects a rotation speed of the crankshaft; a propeller shaft configured to be coupled to a propeller; a shift switch arranged to switch between a engaged state in which rotation of the crankshaft is transmitted to the propeller shaft and a neutral state in which transmission of rotation between the crankshaft and the propeller shaft is blocked; a shift state detector configured to detect which of the engaged state and the neutral state the shift switch is in; an intake passage configured to supply air to a combustion chamber of the engine; a throttle valve that is provided in the intake passage and is configured to adjust an air volume to be supplied to the combustion chamber; an intake pressure sensor configured to detect an intake pressure inside the intake passage; and a control unit configured to receive inputs of detection values from the rotation speed detector (25, 74), the shift state detector and the intake pressure sensor, and is configured or programmed to determine that the crankshaft is reversely rotated in a direction opposite to the forward rotation direction by an external force input from the propeller shaft when a predetermined reverse rotation recording condition is satisfied, and that stores reverse rotation information, characterized in that the intake pressure sensor is configured to detect an intake pressure inside the intake passage wherein the said intake pressure sensor is disposed between the throttle valve and the combustion chamber, wherein the said predetermined reverse rotation recording condition includes a first condition that an intake pressure after the shift switch switches from the neutral state to the engaged state while the crankshaft rotates in the forward rotation direction is larger than a first value equal to or higher than an atmospheric pressure, wherein the control unit is configured or programmed to perform misfire control of the engine when it is determined that the crankshaft is reversely rotating, wherein the said determination that the crankshaft is reversely rotating is based on a pulse output corresponding to rotation of the crankshaft, and the control unit is configured or programmed to store the reverse rotation information when the said predetermined reverse rotation recording condition is satisfied after the said misfire control is performed in accordance with the said determination that the crankshaft is reversely rotating based on the pulse output corresponding to rotation of the crankshaft.