PROBLEM TO BE SOLVED: To provide a cutting blade which can form a slit in an elastic thin film with high dimensional accuracy, and a method for manufacturing a valve body with use of the cutting blade.SOLUTION: A cutting blade 10 which is inserted in one face 21a of an elastic thin film 20 from a vertical direction Z, and is caused to penetrate to the other face 21b of the elastic thin film 20, thereby forming a linear slit 22. The cutting blade 10 comprises a base body part 11 and a blade tip. The base body part 11 has two end parts 12, 13 which are parallel to the cutting blade 10 insertion direction Z, has blade tips 12a, 13a and 14a at two end parts 12, 13 and an end part 14 on an insertion side of the elastic thin film 20, and has at least one a blade peak 15 at the end part 12 on the insertion side.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2020,JPO&INPIT【課題】弾性薄膜に高い寸法精度でスリットを形成することが可能な切断刃、及びその切断刃を用いた医療用弁体の製造方法を提供する。【解決手段】弾性薄膜２０の一方の面２１ａに垂直方向Ｚから刺し入れ、弾性薄膜２０の他方の面２１ｂまで貫通させて直線状のスリット２２を形成する切断刃１０であって、基体部１１と刃先とからなり、基体部１１が、切断刃１０を刺し入れる方向Ｚに対して平行な２つの端部１２及び１３を有し、２つの端部１２及び１３と弾性薄膜２０に刺し入れる側の端部１４とに刃先１２ａ、１３ａ及び１４ａを有し、刺し入れる側の端部１２に刃山１５を少なくとも１つ有する切断刃１０とする。【選択図】図１
