A sacrificial electrode attachment structure includes: a first pipe in which electrolyte flows; a second pipe which is formed of an insulating material and allows the electrolyte to flow; a cylindrical sacrificial electrode unit arranged between the first pipe and the second pipe so as to allow the electrolyte to flow, and including a sacrificial electrode that contacts the electrolyte; a first pipe joint adapted to liquid-tightly connect the first pipe to the sacrificial electrode unit in a detachable manner; and a second pipe joint adapted to liquid-tightly connect the second pipe to the sacrificial electrode unit in a detachable manner.