A hair clip includes an upper clip piece defined with a lip portion, an arched body portion, an upper pivot portion and an upper handle portion; a lower clip piece defined with a tip portion, a base portion, a lower pivot portion, and a lower handle portion; and teeth extending downwards to the base portion. A hair clip is switchable between an open configuration and a closed configuration by operating upper and lower handle portions to have upper and lower clip pieces pivot on upper and lower pivot portions. When the hair clip is in the open configuration, the lip portion is apart from the tip portion for receiving hair therefrom. When the hair clip is in the closed configuration, the lip portion overbites the tip portion so that the hair in the hair-accommodating space is sharply separated from adjacent hair which is excluded from the hair clip.