The invention aims to improve fuel efficiency during cruising at a constant speed by increasing depression reaction force before a driver intends to sharply increase speed. An accelerator pedal reaction force control device (1) for controlling the depression reaction force (Fr) of an accelerator pedal (2) provided in a car is provided with a reaction force actuator (3) for applying the depression reaction force (Fr) to the accelerator pedal (2), a target reaction force setting unit (16) for setting a target depression reaction force (Frt), and a car speed maintenance depression amount setting unit (12) for setting, as a car speed maintenance depression amount ([theta][alpha]), the depression amount of the accelerator pedal (2) to maintain a current car speed (V), and when the pedal depression amount ([theta] [alpha]) exceeds the car speed maintenance depression amount ([theta] [alpha]), the target reaction force setting unit (16) executes a cruising assist in which the target depression reaction force (Frt) is set to the value of cruising assist depression reaction force (Fr[alpha]).