PROBLEM TO BE SOLVED: To provide a field work machine capable of offering an automatic control over the field work having an automatic travelling mechanism so that a transition point from a work travelling mode to a non-work travelling mode can be precisely detected, thereby leaving a headland reliably.SOLUTION: A field work machine includes: a travelling machine body 1; a field work device 2 for executing a farm work on a field; a field information storage section 71a for storing field information containing filed ridge map data; a work information storage section 71b for storing work device information containing work zone in traverse direction with respect to the travelling direction of the field work device 2; a GPS module 5 for outputting positioning data; and a work control signal generation section 83 for generating a work control signal for the field work device 2 in order to leave a prescribed headland during the travelling work on the basis of the map data, positioning data, and the work device info