Abstract: A knife comprises a knife handle or grip having a channel for receiving slidably therein a blade holder having a blade secured thereto so that the blade is withdrawn outwardly as it wears out. A series of notches are formed in the knife grip, while a V-like leaf spring is mounted on the blade holder, whereby the blade holder and hence the blade are held securely at predetermined indexed positions relative to the knife grip through engagement between the V-like leaf spring and the selected notch. A locking structure releasably locks the V-like spring member so that the latter is prevented from being accidently disengaged from the notch.