A multiple-color weft inserting apparatus (60,70) of a fluid jet loom includes at least three weft supply lines (L), a weft-insertion controlling device (65,75). The controlling device (65,75) performs grouping of weft supply lines (L), and performs multiple-color weft insertion (60,70) in accordance with a predetermined weft-insertion pattern using the weft supply lines (L) in the group and at least one remaining weft supply line (L). The weft supply lines (L) in the group are where the weft of the same type is set. In the case where the controlling device (65,75) executes the insertion of the weft of the type corresponding to the group while the weft supply lines (L) in the group successively operate by turns, when the weft supply sensor (3) of any weft supply line (L) in the group detects a weft supply abnormality, the controlling device (65,75) excludes the any weft supply line (L) and continues the insertion of the weft of the type corresponding to the group using the other weft supply line or lines (L) in the group.