To enable an interval between electrodes to be regulated correctly by inserting required number of sheets of interval adjusting rings of a required thickness between the negative electrode position reference surface of an insulating material and a reference flange of a negative electrode in the case of a DC arc thruster adequate to an artificial satellite, etc., to which thruster agent is ejected after being heated in expansion by an arc.

A thrust agent 57 is supplied to the thrust agent expansion part 37 of a positive pole 34 via thrust agent passages 55, 56 formed in a positive pole 34 and an insulating material 40 and an arc is generated between the tip ends of the positive pole 34 and a negative pole 46, the thrust agent 57 is heated in expansion by the arc energy to be sprayed from a nozzle part 38. According to such a method, a large thrust can be generated for long hours by means of a small amount of thrust agent 57. In such a DC arc thruster like this, when an electrode interval 59 between the positive pole 34 and the negative pole 46 is regulated, required number of interval adjusting rings 44 of a required thickness are inserted in a space between the negative pole position reference surface 41 of the insulating material 40 and the reference flange 45 of the negative pole 46. Thereby, the electrode interval 59 is made adjustable so as to facilitate its manufacture.