An extreme ultraviolet light source apparatus , comprising: a disk-shaped cathode ; a first rotational shaft made of a metal to which the cathode is connected; a disc-shaped anode disposed apart from the cathode ; a second rotational shaft made of a metal to which the anode is connected; a first tin supplier configured to coat the cathode with liquid-phase tin ; a second tin supplier configured to coat the anode with liquid-phase tin ; an energy beam irradiation device configured to irradiate the tin on the cathode with an energy beam to vaporize the tin and generate gas-phase tin in a gap between the cathode and the anode ; an electric power supply configured to supply electric power to the cathode and anode to cause a discharge between the cathode and anode for generating a plasma in the gap between the cathode and anode , the plasma emitting extreme ultraviolet light; a first support structure made of a metal supporting the cathode ; and a second support structure made of a metal supporting the anode , the first support structure and the second support structure being not in contact with each other, the first support structure having a first support wall portion and a first tubular portion protruding from the first support wall portion and surrounding the first rotational shaft , the first tubular portion being disposed between the first support wall portion and the cathode , the second support structure having a second support wall portion and a second tubular portion protruding from the second support wall portion and surrounding the second rotational shaft , the second tubular portion being disposed between the second support wall portion and the anode , the first support wall portion and the second support wall portion overlapping each other, the first support wall portion having a through-hole through which the second tubular portion is inserted, or the second support wall portion having a through-hole through which the first tubular portion is inserted. a disk-shaped cathode ; a first rotational shaft made of a metal to which the cathode is connected; a disc-shaped anode disposed apart from the cathode ; a second rotational shaft made of a metal to which the anode is connected; a first tin supplier configured to coat the cathode with liquid-phase tin ; a second tin supplier configured to coat the anode with liquid-phase tin ; an energy beam irradiation device configured to irradiate the tin on the cathode with an energy beam to vaporize the tin and generate gas-phase tin in a gap between the cathode and the anode ; an electric power supply configured to supply electric power to the cathode and anode to cause a discharge between the cathode and anode for generating a plasma in the gap between the cathode and anode , the plasma emitting extreme ultraviolet light; a first support structure made of a metal supporting the cathode ; and a second support structure made of a metal supporting the anode , the first support structure and the second support structure being not in contact with each other, the first support structure having a first support wall portion and a first tubular portion protruding from the first support wall portion and surrounding the first rotational shaft , the first tubular portion being disposed between the first support wall portion and the cathode , the second support structure having a second support wall portion and a second tubular portion protruding from the second support wall portion and surrounding the second rotational shaft , the second tubular portion being disposed between the second support wall portion and the anode , the first support wall portion and the second support wall portion overlapping each other, the first support wall portion having a through-hole through which the second tubular portion is inserted, or the second support wall portion having a through-hole through which the first tubular portion is inserted. <EOS>