A bow for a crossbow includes a retainer, two holders, two limbs, two mounting members and two fastening members. The retainer has two inclined surfaces having a receiving recess. Each holder is mounted on one of the inclined surfaces and includes a base, a cover and a semicircular pivot. The semicircular pivot is mounted detachably on the outer end of the base and corresponds to and abuts with the receiving recess of the inclined surface. Each buffer is mounted between one of the limbs and the base of a corresponding holder for absorbing the force applied to the limb and reducing stress concentration to prolong the useful life of the limb.