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 travel route section of the target travel route to travel based on manual operation input when shifting from manual steering travelling to automatic steering travelling, or in the middle of the automatic steering travelling.SELECTED DRAWING: Figure 1
