PURPOSE: To compact a conveyance system itself and clean a carrier car and a supply line using a blow suction pipe by arranging a weft yarn package supply line in a space in a blow cleaner.

CONSTITUTION: In a system for conveying a weft yarn package to a loom, a supply line (T) carrying a package carrier car (V) capable of performing a reciprocating motion, receiving a weft yarn package (W) on a circulation line and supplying it to a loom is attached to the end part of a horizontal frame (b4) extending in the horizontal direction from a support (b3) supporting a rail (R) for a blow cleaner in an upper space formed by a porch-shaped suction pipe (b2) of the blow cleaner (B) arranged along a row of looms. According to a requirement of a loom in which an empty bobbin is produced, a specific weft yarn package (W) circulating on the circulation line is received at a delivery station and a carrier car is conveyed to a package stand of a specific loom so as to receive the empty bobbin and to deliver a new weft yarn package (w).