A selectively one-way wrench includes a lever, a toothed wheel inserted in the lever, two claws inserted in the lever, a switch operable to engage a selected one of the claws with the toothed wheel and disengage the other claw from the toothed wheel to cause the lever to rotate the toothed wheel via the selected claw only in a selected one of two directions. The selectively one-way wrench further includes a central spring and two lateral springs. The central spring includes two reduced sections each connected to a lateral face of a corresponding one of the claws and an enlarged section formed between the reduced sections. Each of the lateral springs includes a connecting section connected to a rear face of a corresponding one of the claws and an end for abutment against a portion of the lever to push the corresponding claw to engagement with the toothed wheel.