PURPOSE: To freely move and fix a mast by arranging a step guide rail provide with a number of teeth, in the longitudinal direction both before and behind a sailing board and also arranging teeth operation levers that are pressed by a spring before and behind a mast step proveded with a mast support device at the upper part.

CONSTITUTION: A step guide rail with a number of teeth 9 is provided along the longitudinal direction both before and behind a sailing board main frame. A chevron shaped actuating levers 26 are arranged both before and behind a mast step provided with the support device 16 of a mast 15 at the upper part, so as to be freely pressed against a coil spring 29 by means of a pedal member 23. An inclined lower surface 31 and teeth engagement section 27 are formed on the operation lever 26. Then, the mast can freely be moved, fixed, and supported by operating the pedal member 23 to release the engagement with the teeth 9.