This surgical bone preparation instrument (1) comprises a main body (5) terminated by a contacting surface (50) adapted to abut on a bone (B), and a sliding body (7) equipped with a cutting element (3) and which is movable in translation with respect to the main body (5). The bone preparation instrument (1) includes a cutting depth control ring (11) that is adjustable by a single hand, which forms an abutment surface (110) against the movement of one of the main body (5) and the sliding body (7) when the sliding body (7) reaches an adjusted cutting depth (D) corresponding to an adjustment position of the control ring (11).