A train control system comprising: an on-board device that is mounted on each train traveling on a predetermined track; a vehicle radio set that is configured to transmit and receive information of the on-board device; wayside radio sets each of which is disposed at a predetermined location on the ground to transmit information to and receive information from the vehicle radio set; a ground device that is placed by the track and connected to the wayside radio sets; an operation controlling device that is configured to transmit operation information of each train to the ground device; and an interlocking device that is configured to perform an operation control of a turnout for switching tracks, wherein the ground device is configured to detect train locations based on wireless propagation time between the vehicle radio set and the wayside radio set, to receive train entering track information from the operation controlling device, and to control an interval between a preceding train and a following train, wherein a predetermined range around the turnout is set as a detector locking section, when the preceding train passes through the turnout, which prevents entry of-the following train, and an approach point as a stop target of the following train is set before the detector locking section; wherein a location of the approach point is set so that a switching operation and locking of the turnout are completed while the following train travels from the approach point to a point just before the detector locking section, wherein the ground device is configured to: determine whether or not the following train enters a track which differs from the track on which the preceding train entered, based on the train entering track information transmitted from the operation controlling device; when the following train enters a track which differs from the track on which the preceding train entered, calculate traveling speed of the following train so that time until the preceding train passes through the detector locking section and time until the following train reaches the approach point become the same; and transmit the calculated traveling speed to the on-board device mounted on the following train, wherein the following train travels in a state in which traveling speed is controlled on the basis of the traveling speed received by the on-board device, wherein after the preceding train passes through the detector locking section, the turnout is switched to the track on which the following train enters and locked by the interlocking device, and when a detector lock based on the preceding train is released, the stop target of the following train is reset to a normal position. an on-board device that is mounted on each train traveling on a predetermined track; a vehicle radio set that is configured to transmit and receive information of the on-board device; wayside radio sets each of which is disposed at a predetermined location on the ground to transmit information to and receive information from the vehicle radio set; a ground device that is placed by the track and connected to the wayside radio sets; an operation controlling device that is configured to transmit operation information of each train to the ground device; and an interlocking device that is configured to perform an operation control of a turnout for switching tracks, wherein the ground device is configured to detect train locations based on wireless propagation time between the vehicle radio set and the wayside radio set, to receive train entering track information from the operation controlling device, and to control an interval between a preceding train and a following train, wherein a predetermined range around the turnout is set as a detector locking section, when the preceding train passes through the turnout, which prevents entry of-the following train, and an approach point as a stop target of the following train is set before the detector locking section; wherein a location of the approach point is set so that a switching operation and locking of the turnout are completed while the following train travels from the approach point to a point just before the detector locking section, wherein the ground device is configured to: determine whether or not the following train enters a track which differs from the track on which the preceding train entered, based on the train entering track information transmitted from the operation controlling device; when the following train enters a track which differs from the track on which the preceding train entered, calculate traveling speed of the following train so that time until the preceding train passes through the detector locking section and time until the following train reaches the approach point become the same; and transmit the calculated traveling speed to the on-board device mounted on the following train, wherein the following train travels in a state in which traveling speed is controlled on the basis of the traveling speed received by the on-board device, wherein after the preceding train passes through the detector locking section, the turnout is switched to the track on which the following train enters and locked by the interlocking device, and when a detector lock based on the preceding train is released, the stop target of the following train is reset to a normal position.