Ski boot device for ski boots (1). Ski boots have a front sole section (3) with a front interaction surface associated with binding and releasing from a front ski binding, and a rear sole section (4), in a common plane (8), with a rear interaction surface associated with binding and releasing from a rear ski binding. The ski boot device of the present invention is attached to the ski boot and comprises a toe portion formed and attached to the ski boot sole (3) without interfering with the front interaction surface during binding or releasing, a heel portion formed and attached to the heel (4) of the ski boot without interfering with the rear interaction surface during binding or releasing; and a support portion (10A, 10B) provided intermediate the toe portion and heel portion and having a shaped profile which extends below the common plane and provides a contact surface during walking.