A sharpening tool includes a main base (10) having a mounting seat (12) provided with a first receiving recess (121) and a second receiving recess (122), two first grinding blades (13) mounted in the first receiving recess, an attachment device (11) mounted on the main base, a grinding unit (20) mounted on the mounting seat, and a cover (30) mounted on the mounting seat. The grinding unit includes a second grinding blade (21) mounted in the second receiving recess and having a grinding face (211), and a catch plate (23) mounted on the second receiving recess and having an abutting portion (231) facing the grinding face of the second grinding blade. The first grinding blades provide a double-side grinding function, and the second grinding blade provides a one-side grinding function.