A driving assistance system comprising: a target detecting unit (10, 20) configured to detect a target around a subject vehicle; an operation amount detecting unit (10, 21) configured to obtain an accelerating operation amount corresponding to an operation amount of a driver of the subject vehicle; a speed detecting unit (10, 23) configured to detect a vehicle speed, the vehicle speed being a speed of the subject vehicle; and a pre-collision control implementing unit (10, 30, 32, 34, 36, 38) configured to perform pre-collision control for avoiding a collision with the target, based on the vehicle speed at a point in time at which the accelerating operation amount becomes equal to or larger than a first operation amount threshold value, based on a predetermined control start condition including an essential condition that both a first condition and a second condition are established, the first condition being that a collision index value having a correlation with a possibility of collision between the target and the subject vehicle, the collision index value being calculated based on target information, the target information including a relative position of the target relative to the subject vehicle, the target information including a relative velocity of the target relative to the subject vehicle, satisfies a predetermined index value condition, the second condition being that the accelerating operation amount is equal to or larger than a control threshold value, and based on a permission condition that the accelerating operation amount is equal to or larger than the first operation amount threshold value at a point in time at which the vehicle speed is equal to or less than a speed threshold value; wherein the pre-collision control implementing unit (10, 30, 32, 34, 36, 38) is configured, when the predetermined control start condition is satisfied, to perform the pre-collision control when the permission condition has in the past been established by a point in time at which the predetermined control start condition is satisfied, and not to perform the pre-collision control when the permission condition has not been established by the point in time at which the predetermined control start condition is satisfied. a target detecting unit (10, 20) configured to detect a target around a subject vehicle; an operation amount detecting unit (10, 21) configured to obtain an accelerating operation amount corresponding to an operation amount of a driver of the subject vehicle; a speed detecting unit (10, 23) configured to detect a vehicle speed, the vehicle speed being a speed of the subject vehicle; and a pre-collision control implementing unit (10, 30, 32, 34, 36, 38) configured to perform pre-collision control for avoiding a collision with the target, based on the vehicle speed at a point in time at which the accelerating operation amount becomes equal to or larger than a first operation amount threshold value, based on a predetermined control start condition including an essential condition that both a first condition and a second condition are established, the first condition being that a collision index value having a correlation with a possibility of collision between the target and the subject vehicle, the collision index value being calculated based on target information, the target information including a relative position of the target relative to the subject vehicle, the target information including a relative velocity of the target relative to the subject vehicle, satisfies a predetermined index value condition, the second condition being that the accelerating operation amount is equal to or larger than a control threshold value, and based on a permission condition that the accelerating operation amount is equal to or larger than the first operation amount threshold value at a point in time at which the vehicle speed is equal to or less than a speed threshold value; wherein the pre-collision control implementing unit (10, 30, 32, 34, 36, 38) is configured, when the predetermined control start condition is satisfied, to perform the pre-collision control when the permission condition has in the past been established by a point in time at which the predetermined control start condition is satisfied, and not to perform the pre-collision control when the permission condition has not been established by the point in time at which the predetermined control start condition is satisfied.