A calculus crushing apparatus includes a flexible sheath for insertion into a body cavity and an operation wire slidably inserted in the sheath. A basket for holding a calculus is fixed to the distal end of the operation wire. The basket is formed of a plurality of elastic wires. A connecting rod is connected to the proximal end of the operation wire. By moving the connecting rod by an operation mechanism, the operation wire slides in the sheath, so that the basket is projected from or retracted in the sheath. The connecting rod has a disconnecting portion which is weaker than the elastic wires and operation wire against tension.