To provide a tensioner which can circulate a sufficient amount of oil even if there is a long time lag until pressurized oil starts to be supplied, and which exhibits a lower level of leak of oil stored therein, and which is structured simply without increasing the number of components therefore. The tensioner includes: a tensioner body having a plunger bore; a cylindrical plunger slidably inserted into the plunger bore; and biasing means for urging the plunger outward. When the tensioner is fixed to a wall surface, a body hole that extends from the wall surface up to a circumferential surface of the plunger bore is located lower than an oil discharge hole in the wall surface.