LACHRYMAL SAC INCISION KNIFE

[Object]The object of the invention is to provide with a rational construction technique of the lacrimal sac incision knife.[Means to achieve the object]A Lacrimal sac incision knife 1 which is insertable into nasal cavity of patient, the lacrimal sac incision knife incising the lacrimal sac located in the back of the nasal cavity,wherein the stabbing blade 60 defines the lacrimal sac stabbing portion, the first side blade 61 defines the first lacrimal sac incision portion and the second side blade 62 defines the second lacrimal sac incision portion,the blade portion 6 has a length size of approximately from 4.0 mm to 7.0mm in the longitudinal direction, a maximum width size of approximately from 1.4 mm to 2.0 mm in the width direction,the stabbing blade 60 has a blade length size of approximately 1.2 mm in the longitudinal direction, a maximum width size of approximately from 1.2 mm to 1.5 mm in the width direction,the first side blade 61 and the second side blade 62 respectively have a blade length size of approximately 3.0 mm to 5.0 mm in the longitudinal direction.