To provide an anode anti-corrosion unit of an engine for an outdoor motor capable of easily recognizing a replacement time of an anode metal.

The anode anti-corrosion unit 26 of the engine for the outdoor motor is the one in which the anode metal 54 is mounted on a cylinder block 23 constituting a water jacket 45. The anode anti-corrosion unit 26 includes: an anode current detection part 62 for detecting a current I which flows with potential difference between the cylinder block and the anode metal; a part 63 for determining the replacement time which determines that it is the replacement time of the anode metal when the current detected at the anode current detection part is below a preset reference current; and an informing part 67 for informing the determination result of the part for determining the replacement time.