A steering control device that controls a steer-by-wire steering system for a vehicle, the steering control device comprising: a steering operation control circuit that controls a steering operation actuator of the steer-by-wire steering system in accordance with a steering state of a steering wheel, the steering system including a reaction force actuator that applies a steering reaction force against an operation of the steering wheel, and a steering operation actuator that steers steered wheels via a steering operation shaft under a condition where power is not transmitted between the steered wheels and the steering wheel; and a reaction force control circuit that calculates the steering reaction force (Fir), wherein the reaction force control circuit includes: a first estimated axial force calculation circuit (M100ac) that calculates a first estimated axial force (Fer) based on road surface information; characterized in that the reaction force control circuit further includes: a second estimated axial force calculation circuit (M100aae) that calculates a second estimated axial force (Fy) applied to the steering operation shaft based on a vehicle state quantity; and a grip factor calculation circuit (M100aaf) that calculates a grip factor (Gr) based on the first estimated axial force (Fer) and the second estimated axial force (Fy), and wherein the reaction force control circuit varies the steering reaction force (Fir) in accordance with the grip factor (Gr). a steering operation control circuit that controls a steering operation actuator of the steer-by-wire steering system in accordance with a steering state of a steering wheel, the steering system including a reaction force actuator that applies a steering reaction force against an operation of the steering wheel, and a steering operation actuator that steers steered wheels via a steering operation shaft under a condition where power is not transmitted between the steered wheels and the steering wheel; and a reaction force control circuit that calculates the steering reaction force (Fir), wherein the reaction force control circuit includes: a first estimated axial force calculation circuit (M100ac) that calculates a first estimated axial force (Fer) based on road surface information; characterized in that the reaction force control circuit further includes: a second estimated axial force calculation circuit (M100aae) that calculates a second estimated axial force (Fy) applied to the steering operation shaft based on a vehicle state quantity; and a grip factor calculation circuit (M100aaf) that calculates a grip factor (Gr) based on the first estimated axial force (Fer) and the second estimated axial force (Fy), and a first estimated axial force calculation circuit (M100ac) that calculates a first estimated axial force (Fer) based on road surface information; characterized in that the reaction force control circuit further includes: a second estimated axial force calculation circuit (M100aae) that calculates a second estimated axial force (Fy) applied to the steering operation shaft based on a vehicle state quantity; and a grip factor calculation circuit (M100aaf) that calculates a grip factor (Gr) based on the first estimated axial force (Fer) and the second estimated axial force (Fy), and wherein the reaction force control circuit varies the steering reaction force (Fir) in accordance with the grip factor (Gr).