A liquid component collecting device capable of more easily collecting a liquid component. A liquid component collecting device(100) is provided with: a flexible cylindrical liquid component storage container (21) having an opening at one end thereof; a cylindrical first housing container (22) for housing the liquid component storage container (21) and having an opening at one end thereof; and a first cap (23) connected to the opening in the liquid component storage container (21) and fitted to the opening in the first housing container (22). A pressure regulating space (26) independent of the internal space of the liquid component storage container (21) is formed between the outer side of the liquid component storage container (21) and the inner side of the first housing container (22). The first cap (23) is provided with a liquid component inlet channel (27) for introducing blood into the liquid component storage container (21), a first communication channel (28) communicating with the internal space of the liquid component storage container (21), and a second communication channel (29) communicating with the pressure regulating space (26).