A drive support device that supports driving operation of a vehicle, comprising: a vehicle speed sensor that detects a current vehicle speed of the vehicle; an infrastructure communication unit that acquires information about a signal cycle that is a cycle at which indication of a traffic signal arranged in a travelling direction of the vehicle changes, wherein the signal cycle includes lighting cycle and signal change timing; a position calculation unit that calculates relative positional information between the vehicle and the traffic signal; a target vehicle speed control unit that calculates a reference target vehicle speed range of the vehicle, in which the vehicle is able to pass through a traffic signal point at which a traffic signal is arranged while the traffic signal is in a passage allowing indication state, on the basis of the relative position between the vehicle and the traffic signal point and information about the signal cycle of the traffic signal, sets an indication upper limit speed on the basis of the current vehicle speed detected by the vehicle speed sensor, and determines a target vehicle speed range that is a speed range lower than or equal to the indication upper limit speed on the basis of the reference target vehicle speed range; and a target vehicle speed indicating unit that indicates the target vehicle speed range determined by the target vehicle speed control unit, characterized in that when a difference in speed between the upper limit and a lower limit of the reference target vehicle speed range is smaller than or equal to a predetermined value, the target vehicle speed control unit does not indicate the target vehicle speed range on the target vehicle speed indicating unit. a vehicle speed sensor that detects a current vehicle speed of the vehicle; an infrastructure communication unit that acquires information about a signal cycle that is a cycle at which indication of a traffic signal arranged in a travelling direction of the vehicle changes, wherein the signal cycle includes lighting cycle and signal change timing; a position calculation unit that calculates relative positional information between the vehicle and the traffic signal; a target vehicle speed control unit that calculates a reference target vehicle speed range of the vehicle, in which the vehicle is able to pass through a traffic signal point at which a traffic signal is arranged while the traffic signal is in a passage allowing indication state, on the basis of the relative position between the vehicle and the traffic signal point and information about the signal cycle of the traffic signal, sets an indication upper limit speed on the basis of the current vehicle speed detected by the vehicle speed sensor, and determines a target vehicle speed range that is a speed range lower than or equal to the indication upper limit speed on the basis of the reference target vehicle speed range; and calculates a reference target vehicle speed range of the vehicle, in which the vehicle is able to pass through a traffic signal point at which a traffic signal is arranged while the traffic signal is in a passage allowing indication state, on the basis of the relative position between the vehicle and the traffic signal point and information about the signal cycle of the traffic signal, sets an indication upper limit speed on the basis of the current vehicle speed detected by the vehicle speed sensor, and determines a target vehicle speed range that is a speed range lower than or equal to the indication upper limit speed on the basis of the reference target vehicle speed range; and a target vehicle speed indicating unit that indicates the target vehicle speed range determined by the target vehicle speed control unit, characterized in that when a difference in speed between the upper limit and a lower limit of the reference target vehicle speed range is smaller than or equal to a predetermined value, the target vehicle speed control unit does not indicate the target vehicle speed range on the target vehicle speed indicating unit.