than 1 3 m by moving a carriage 11 carrying thereon the workpiece 10 gases coming out of the weld portion can be prevented from entering the electron gun 12 resulting in a sound weld furthermore since the second beam adjusting means 28 can be displaced along the path of the electron beam 25 to a desired position by rotating the position setting arm 20 the electron beam can be focused accurately on the weld portion 101 thus producing sound deeply penetrating welds the electron beam welding machine of this invention also has the following advantage the second beam adjusting means 28 is mounted to the position setting arm 20 through the position adjusting means 29 including the adjusting mechanisms such as the rotary adjusting mechanism made up of the motor 33 and belt 34 the x axis adjusting mechanism driven by the motor 38 and ball screw 37 and the y axis adjusting mechanism driven by the motor 41 and ball screw 40 therefore if the position setting arm 20 the position adjusting means 29 or the second beam adjusting means 28 was not assembled to the exactly correct position the center of magnetic field of the second beam adjusting means 28 can be aligned.