A half plain bearing which can minimize lubricant leakage while retaining a crush relief function, comprising: grooved portions formed circumferentially on an inner surface of the half plain bearing; protrusions of the grooved portions in a secondary loaded portion being liable to running-in wear caused by contact with a shaft. Consequently, the protrusions undergo running-in wear through contact with the rotating shaft at an early stage. The worn protrusions serve the same purpose as crush reliefs, providing a crush relief function even though no crush relief is formed. This makes it possible to minimize lubricant leakage.