PROBLEM TO BE SOLVED: To provide a work machine which forms clean ridges while ensuring straight-advancing performance of a travel machine in a wet paddy field.SOLUTION: A work machine comprises an operation unit, reference value setting means, operation direction detection means, operation position detection means, an operation direction adjustment mechanism, an operation position adjustment mechanism, and control means. The operation position detection means detects a moving average value in an extention direction of an off-set width of the operation unit. The control means has: a normal operation mode which maintains an operation position and an operation direction in a predetermined state an automatic straight-advancing operation control mode which adjusts the changes in the operation position and the operation direction according to a change in a travel direction of a traveling machine body by using reference values of the operation direction and the operation position which are set on the basis of detection values in the normal operation mode and a wet paddy field mode which changes a control parameter of the automatic straight-advancing operation control mode so as to expand a dead zone in an extension direction of an off-set width of the operation unit in the operation position detection means if the moving average value of a certain level or higher is detected by the operation position detection means.
