PURPOSE: To extend a service life by making a through-hole in a plate before coated, when manufacturing the plate with a coated surface having the through- hole, so that a machining tool should be only designed so as to be adjusted to a plate material.

CONSTITUTION: A plate 10 is used as, e.g. a plate with a path. The plate 10 formed of, e.g. metal is open to upper and lower faces and has punched path 12 and hole 14. The plate 10 is coated at its sides with an adhesive elastomer plastic sheet 16. A sheet 16 is provided as a seal member. In this case, before the plate 10 is coated with the sheet 16, the path 12 and the hole 14 are made in the plate 10. So, a machining tool should be only designed so as to be adjusted to a plate material. Less machining errors and a higher machining speed are ensured.