A lash adjuster is provided of which an adjusting screw can be repeatedly fixed in position.The lash adjuster includes a nut member 14 having an internal thread 15 on an inner periphery thereof, an adjusting screw 17 having a external thread 16 on the outer periphery thereof which is in threaded engagement with the internal thread 15, and a return spring 19 biasing the adjusting screw 17 in the direction to protrude from the nut member 14, wherein the lash adjuster further includes an initial setting member 25 detachably disposed between the adjusting screw 17 and the nut member 14, and wherein the adjusting screw 17 is fixed to the nut member 14 due to frictional forces between the initial setting member 25 and the adjusting screw 17 and between the initial setting member 25 and the nut member 14.