A depression force estimation device for a brake pedal, the device comprising: a first deceleration calculation unit (60, S23) that calculates a first estimated vehicle body deceleration by using a wheel speed sensor (SE2, SE3, SE4, SE5) arranged on the vehicle; a gradient acquisition unit (60, S24, S86, S90) that acquires a gradient change of the first estimated vehicle body deceleration; and a depression force determination unit (60, S90) that determines whether a depression force applied to the brake pedal by the driver is high, wherein a first deceleration determination value (DV_st) and a second deceleration determination value (G_st) are set, and wherein the gradient acquisition unit is configured to acquire, as a first gradient change, a gradient change of the first estimated vehicle body deceleration at the point in time when the first estimated vehicle body deceleration exceeds the first deceleration determination value (DV_st), characterized in that the depression force estimation device further comprises a second deceleration calculation unit (60, S27) that calculates a second estimated vehicle body deceleration by using a vehicle body acceleration sensor arranged on the vehicle; the gradient acquisition unit is configured to acquire, as a second gradient change, a gradient change of the first estimated vehicle body deceleration in a case in which the second estimated vehicle body deceleration has exceeded the second deceleration determination value (G_st), and the depression force determination unit (60, S90) is configured to determine that the depression force applied to the brake pedal by the driver is high in a case in which the second gradient change is greater than or equal to the first gradient change. a first deceleration calculation unit (60, S23) that calculates a first estimated vehicle body deceleration by using a wheel speed sensor (SE2, SE3, SE4, SE5) arranged on the vehicle; a gradient acquisition unit (60, S24, S86, S90) that acquires a gradient change of the first estimated vehicle body deceleration; and a depression force determination unit (60, S90) that determines whether a depression force applied to the brake pedal by the driver is high, wherein a first deceleration determination value (DV_st) and a second deceleration determination value (G_st) are set, and wherein the gradient acquisition unit is configured to acquire, as a first gradient change, a gradient change of the first estimated vehicle body deceleration at the point in time when the first estimated vehicle body deceleration exceeds the first deceleration determination value (DV_st), characterized in that the depression force estimation device further comprises a second deceleration calculation unit (60, S27) that calculates a second estimated vehicle body deceleration by using a vehicle body acceleration sensor arranged on the vehicle; the gradient acquisition unit is configured to acquire, as a second gradient change, a gradient change of the first estimated vehicle body deceleration in a case in which the second estimated vehicle body deceleration has exceeded the second deceleration determination value (G_st), and the depression force determination unit (60, S90) is configured to determine that the depression force applied to the brake pedal by the driver is high in a case in which the second gradient change is greater than or equal to the first gradient change.