Abstract: The invention relates to a seat fixing device, in particular to an air passenger seat on a floor of an aircraft comprising at least one fastening rail (10) in the form or a hollow profile which is provided with a longitudinal channel (14) delimiting the free flanks (16) of the profile on the top part thereof (12) oriented to the scat, wherein said channel comprises through openings (18) disposed in a predetermined modular dimension which enlarge the free input section and are used for inserting at least one snap-locking part (24) of a locking body (26) which is movable to a clamping position with the profile (16) of the hollow profile (14) by the relative displacement of each snap-locking part (24) in a perpendicular direction with respect to the longitudinal axis (28) of the fastening rail (10).