A lash adjuster includes a bottomed cylindrical body and a cylindrical plunger reciprocably inserted into the body and having a bottom wall and a peripheral wall. The plunger has a low-pressure chamber. The peripheral wall of the plunger includes an annular band portion abutting against an upper part of a peripheral wall of the body. The peripheral wall of the plunger has a plurality of plunger oil holes located below the band portion. The plunger oil holes include respective lower ends defining a level of the oil stored in the low-pressure chamber. The plurality of plunger oil holes are located at a common height position of the peripheral wall of the plunger coming close to the band portion.