A packaging container having a container body and a lid unit which is undetachably mounted on the container body. The container body has a neck portion provided with an opening. An external thread cut in the outer periphery of the neck portion, and a lid mounting portion is provided below the external thread. The lid unit has a lid body and a fitting member. The lid body is provided with an internal thread engageable with the external thread of the container body, and has a function of hermetically sealing the opening of the container body. The fitting member is rotatably fitted around the lid mounting portion of the container body, but vertical movement of the fitting member is restricted within a predetermined range. The fitting member is held undetachable from the lid mounting portion by a collar of the container body. The lid body and the fitting member are connected to each other by a connecting member in such a manner that the lower surface of the lid body can rest on and separate from the upper surface of the fitting member.