OUTBOARD MOTOR

PROBLEM TO BE SOLVED: To provide an outboard motor which does not cause upsizing and prevents a gear mechanism from being damaged by wear debris by detecting an amount of wear debris of the gear mechanism with a simple configuration.SOLUTION: The outboard motor which includes a gear case 64 housing the gear mechanism for transmitting a driving force of a prime mover to a propeller, includes: a drain bolt 82 which is closably attached to a drain hole 80 drilled in the gear case and is made of a magnetic material; and a laminated part 86 which is provided on a portion (exposed portion) 82a1 exposed inside the gear case, of the drain bolt, and in which an electric conductor 86a, a first insulator 86b and a resistor 86c brought into local contact with the electric conductor are stacked in the direction of gravitational force. A value of an electric current carried to the drain bolt 82 from the electric conductor 86a by applying a voltage to the electric conductor 86a is detected, and an amount of wear debris of the gear mechanism, which is accumulated on the drain bolt 82, is detected on the basis of the detected value of the electric current.