To provide a method and device for manufacturing garnish gaskets capable of forming clear and deep texture on the surface side without deforming the main body.

In the method for manufacturing garnish gaskets 2 composing of the main body 22 for closing joints between building materials such as wall panels or the like and a garnish plate 21 provided texture 210 on the surface side, an extruding plate 219 of the garnish plate 21 is extruded and formed with an extruding die 10, and the garnish plate 21 is formed by pressing with a texture roll 12 for forming texture 210 on the surface side of the extruding plate 219 just after extruding. On the other hand, the main body 22 is formed with the extruding die 10 apart from the garnish plate 21, and next the main body 22 and the garnish plate 21 are joined.