PURPOSE: To prevent electrolyte leakage by friction-welding each other welding ribs installed along an electrolyte passage in each facing parts of facing frames, and by putting flashes generating by welding into a flash trap.

CONSTITUTION: A channel pattern 72 and a channel pattern 62 are arranged in a row on the facing side of adjacent frames in the assembly job, and a separator 16 is welded to an electrode 14 in a welding process. By the welding job, part of the frame is heated and the frame in a welding rib 66 and a kiss rib 68 is melted and the molten flash flows into flash traps 64, 65, and part of the molten flash also flows into the channel pattern 62 without accumulating on the surface 74. Strong leakage preventing welding seal is formed in the welding rib 66 and leakage preventing welding seal is also formed in the kiss ribs 68, 70. Electrolyte leakage from a cell stack is prevented.