A travel control system suitable for a construction machine having: left and right traveling devices (2L, 2R); an engine (5L, 5R) as a power source for the left and right traveling devices (2L, 2R); left and right manipulators for traveling (9L, 9R) that are operated to drive the left and right traveling devices (2L, 2R) respectively; a work device for executing work other than traveling; and a manipulator for work (8L, 8R) that is configured to be operated to drive the work device, the travel control system comprising: a switch for traveling that is provided separately from the left and right manipulators for traveling (9L, 9R) and configured to output a signal to drive and stop both the left and right traveling devices (2L, 2R), a manipulator for steering that is configured to output a signal to change a direction of travel of the traveling devices (2L, 2R) that are being driven based on an operation of the switch for traveling, and travel control means configured to control the left and right traveling devices (2L, 2R) based on operation signals output from the switch for traveling and the manipulator for steering, characterised in that the travel control means is further configured to perform steering control by reducing a speed of either the left or right traveling device (2L, 2R) in accordance with an operation position and operation amount of the manipulator for steering, and lowering a speed of the engine in accordance with the operation amount of the manipulator for steering. left and right traveling devices (2L, 2R); an engine (5L, 5R) as a power source for the left and right traveling devices (2L, 2R); left and right manipulators for traveling (9L, 9R) that are operated to drive the left and right traveling devices (2L, 2R) respectively; a work device for executing work other than traveling; and a manipulator for work (8L, 8R) that is configured to be operated to drive the work device, the travel control system comprising: a switch for traveling that is provided separately from the left and right manipulators for traveling (9L, 9R) and configured to output a signal to drive and stop both the left and right traveling devices (2L, 2R), a manipulator for steering that is configured to output a signal to change a direction of travel of the traveling devices (2L, 2R) that are being driven based on an operation of the switch for traveling, and travel control means configured to control the left and right traveling devices (2L, 2R) based on operation signals output from the switch for traveling and the manipulator for steering, characterised in that the travel control means is further configured to perform steering control by reducing a speed of either the left or right traveling device (2L, 2R) in accordance with an operation position and operation amount of the manipulator for steering, and lowering a speed of the engine in accordance with the operation amount of the manipulator for steering. a switch for traveling that is provided separately from the left and right manipulators for traveling (9L, 9R) and configured to output a signal to drive and stop both the left and right traveling devices (2L, 2R), a manipulator for steering that is configured to output a signal to change a direction of travel of the traveling devices (2L, 2R) that are being driven based on an operation of the switch for traveling, and travel control means configured to control the left and right traveling devices (2L, 2R) based on operation signals output from the switch for traveling and the manipulator for steering, characterised in that the travel control means is further configured to perform steering control by reducing a speed of either the left or right traveling device (2L, 2R) in accordance with an operation position and operation amount of the manipulator for steering, and lowering a speed of the engine in accordance with the operation amount of the manipulator for steering. reducing a speed of either the left or right traveling device (2L, 2R) in accordance with an operation position and operation amount of the manipulator for steering, and lowering a speed of the engine in accordance with the operation amount of the manipulator for steering.