When Polonius suspects Hamlet, he demonstrates symptoms of Paranoid Personality Disorder. Paranoid Personality Disorder is about behaviors of distrust and suspiciousness of other people and believe others’ motives are malevolent. According to the psychology disorder book DSM-V, one of the diagnostic criteria is “preoccupied with unjustified doubts about the loyalty or trustworthiness of friends or associates” (649). Polonius’ Paranoid Disorder is shown in Act 3 Scene 3, Polonius is trying to figure out what is going on with Hamlet, and he believes Hamlet will talk about that to the Queen in private. Shakespeare writes, “My lord, he’s going to his mother’s closet. Behind the arras I’ll convey myself To hear the process. I’ll warrant she’ll tax him home” (3.3.29-32). Due to Hamlet’s unusual behavior, Polonius believes that Hamlet is getting crazy because unrequited love from Ophelia, and Polonius doesn’t trust Hamlet, so his suspiciousness drives him to hide behide the Queen’s closet to figure out what Hamlet is planning, and this action is the main reason that causes his death. On one hand, Polonius’ suspiciousness of Hamlet is totally reasonable, due to Hamlet’s various unusual behaviors, Polonius thinks Hamlet is going to hurt his daughter, King and Queen. The idea of suspiciousness is understandable, on the other hand, the ways he behaves is not appropriate.