A liquid medication (4), a powder medication, or a granular medication is filled into a container body (2) having a tube-like section (2a) and a closed bottom section (2b). After that, in fitting and mountimg a lid body (3) having a tube-like section (3a) and a closing upper end section (3b) to the container body (2), an elongated spatula (5) is caused to be present between both the tube-like sections (2a, 3a) so as to form a gap therebetween to enable air within the container (1) to be released through the gap. Then, the elongated spatula (5) is pulled out to allow the pressure within the container (1) to be equal to the atmospheric pressure, and this prevents the phenomenon that the filled medication (4) leaks from the fitting gap between the container body (2) and the lid body (3) after the container body (2) and the lid body (3) are joined together.
