PURPOSE: To shorten the length of wiring between a circuit in a vessel and a semiconductor element outside the vessel for improving characteristics when a lead-out terminal conductor of a liquid-immersed electric device is passed through a hole formed in a liquid sealing vessel and received in the vessel, by sealing the sections where the terminal conductor is passed through with an insulator while attaching cooling fins to the terminal conductor.

CONSTITUTION: A lead-out terminal 1 of a semiconductor element 4 is passed through a base 3 of a semiconductor device. A pair of threaded holes 11 and 12 are provided at the end 1b of a terminal 1 present outside a closed vessel not shown and the stud- type semiconductor element 4 such as snubber diode or the like is attached to the hole 11 while an electrical wire is connected to the other hole 12. Further, cooling fins 13 are attached to the end 1a of the terminal 1 passed through the base 3, present within the closed vessel. In this manner, it is possible to shorten the length of wiring between the circuit within the container and the semiconductor element of the circuit outside the vessel for decreasing wiring inductance, while it is also possible to discharge heat generated by the semiconductor element 3 outside the vessel to liquid within the container through the lead-out terminal conductor 1 for improving the cooling effect.