PURPOSE: To provide a titled fillet welding machine which performs automatically fillet welding with less drop-out and with high reliability by providing a recess to a welding carriage to expand the range for adjusting the position of a torch and to reduce the size over the entire part and stopping automatically the device when the carriage travel deviates or the contact of the carriage with a corner part is detected.

CONSTITUTION: A recess 8 is provided to a carriage 3 supported by four wheels 1 to expand the range for adjusting the position of the top end of a welding torch 7 and to reduce the size over the entire part. Deviation of the carriage 3 from a weld zone 15 is obviated with respect to the advancing direction by adjusting the projection of guide rollers 6 provided to the carriage 3. In case the carriage deviates from the weld zone, such deviation is detected with a detector 9. If the carriage 3 contacts with a corner part, such contact is detected with a limit switch 10. The travel and welding are then automatically stopped. The drop-out of welding in the corner part is decreased and the carriage is automatically stopped when the carriage travels abnormally, by which the reliability of welding is improved.