NOVELTY - The method involves forming partition (12) and preset alignment mark (13) in surface of base material (11) by resin. The preset alignment mark and a specific alignment mark (14) are formed in predetermined position. The surface of base material is covered by contact bonding layer (17) containing electrolyte. An electrolytic membrane (16) is arranged to overlap the preset alignment mark and specific alignment mark. The heating pressurization of laminated portion is carried out by piling up the base materials.    USE - Manufacturing method of membrane/electrode joined structure for polymer electrolyte fuel cell (claimed) mounted in motor vehicle.    ADVANTAGE - The electrolytic membrane is arranged to overlap the preset alignment mark and specific alignment mark, so that the position alignment of catalyst layer, sealing material, anode catalyst layer, and cathode catalyst layer can be performed efficiently, and the membrane/electrode joined structure can be manufactured easily without the need for performing position shift of catalyst layer. The adhesiveness of catalyst layer and electrolytic membrane can be ensured by forming the contact bonding layer between catalyst layer and electrolytic membrane, so that the durability of membrane/electrode joined structure can be prolonged, and the electric power generation performance can be improved. The need for using excess catalyst ink can be avoided by coating the catalyst ink to desired range, such that the catalyst material loss can be reduced, and the usage-amount of expensive platinum can be reduced. Hence the cost of fuel cell can be reduced.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a base material for catalyst layer formation.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view illustrating the position alignment process.    Base material (11)    Partition (12)    Preset alignment mark (13)    Specific alignment mark (14)    Electrolytic membrane (16)    Contact bonding layer (17)