Provided is a method for producing a liquid medium composition, including using a junction conduit structure 10 having a structure in which a first inlet conduit 11 and a second inlet conduit 12 are joined together to form an outlet conduit 13, and flowing a first liquid 1 containing a particular compound into the first inflow conduit 11 and flowing a second liquid 2 containing a linking substance into the second inlet conduit 12, and allowing the flows of the both liquids to join together to mix the both liquids, thus forming a liquid medium composition 3 containing structures formed by the particular compound linked via the linking substance dispersed therein while being flown through the outlet conduit 13.