PROBLEM TO BE SOLVED: To provide a travelling work machine and an automatic steering system used for the same capable of performing efficient work travelling without imposing a burden on an operator while adopting manual steering and automatic steering.SOLUTION: A travelling work machine and an automatic steering system used for the same include: a positioning unit 5 for outputting positioning data indicative of the position of its own machine; a route calculation part 81 for calculating a target travel route for a travelling machine body 1 to perform work travelling by automatic steering; a steering data output part 82 for outputting automatic steering data for the travelling machine body 1 to travel along the target travel route using the positioning data and the target travel route; an automatic steering part 83 for creating a steering signal for steering the travelling machine body 1 based on the automatic steering data; and a target travel route adjustment part 87 for adjusting at least a certain target
