A sealed type lash adjuster (100A) includes a plunger (2A), a body (1) in which the plunger (2A) is inserted in a fitting manner, a first sealing means (5) provided between the plunger (2A) and the body (1), and a second sealing member (20A) that can prevent or suppress intrusion of an engine oil from an outside. The second sealing means (20A) seals a portion of the plunger (2A) exposed from the body and is arranged so as to cover a clearance (K) formed between an open end portion of the body and the plunger (2A). More specifically, the second sealing member (20A) has a one-end portion (20aA) and an other-end portion (20bA) as sealing parts having a function of preventing or suppressing intrusion of the engine oil from the outside.