To provide a coupler for a drain member, into which the drain member can be easily inserted so that efficiency of coupling work can be made good and which enhances the reliability of coupling by preventing easy slip-off after the coupling.

This coupler for the drain member, which is used for a liquefaction preventing method, etc., is constituted by being formed in an approximately cylindrical shape in such a manner as to make a thermoplastic resin cord-like or linear streak meander. The coupler is characterized as follows: a plurality of fins are radially extended out from a center; irregularities are formed at outside edges of the fins; and partitioning protrusions are provided in approximately intermediate regions of them in a longitudinal direction.