Abstract: The vehicle occupant restraining device includes: a three-point seatbelt device adapted to restrain a vehicle occupant, who is seated at a vehicle seat, by a shoulder belt portion and a lap belt portion of a seatbelt; a rear side restraining portion configured to be disposed at a seatback of the vehicle seat, and spanning between left and right side frames of the seatback, the rear side restraining portion being in a slack state and convex toward a seat rear side; and a pulling device that, by pulling at least one end portion side of the rear side restraining portion, reduces slack of the rear side restraining portion.