To provide a weather strip manufacturing method capable of drawing out a core mold without bringing about the lowering of the sealability or appearance quality of a weather strip or the like when the weather strip, in which an insert or the like is embedded, is manufactured.

The rear lower corner part of the weather strip of a front door becomes a mold forming part 15. The mold forming part 15 is equipped with a base bottom part 31, the side wall part 32 extending to an outer peripheral side from the base bottom part 31 and the hollow seal part 33 integrally formed to the side wall part 32. The flat sheetlike insert 42 is embedded in the side wall part 32. At the time of molding of the mold forming part 15, the core mold for forming a hollow part 46 is drawn out from a position, which is almost opposed to the seal surface 33a with a partner member of the seal part 33 so as to hold the hollow part 46, being the non-embedded position of the insert 42 in the side wall part 32.