A cap body of a cap includes: a cylindrical inner wall section to be fitted into an inner wall surface of a container mouth section; an annular wall section that extends obliquely in an upper direction toward a radial-direction center integrally from an inner wall surface of the cylindrical inner wall section, has a lower wall surface of a truncated conical shape, and has a discharge hole in a radial-direction center portion; a check valve disposed above the annular wall section to open or close the discharge hole in such a manner that a valve section is detached from or seated on an annular valve seat around the discharge hole; and a guiding tubular body disposed above the check valve and having a discharge passage of contents from the discharge hole. Therefore, at the time of using the contents, the contents can be smoothly discharged to the outside.