Colorimetric and wash fastness data after repeated wash cycles of Poly Lactic Acid(PLA) fiber were examined with C. I. Vat Blue 1, also other comparing 2 dyes (C. I. Vat Blue 35, C. I. Vat Blue 5), in this study. The fastness of three vat dyes on PLA fiber to repeated washing according to KS K 0430 A-2 regulation increased with dyeing temperatures. The $L^*$ values of the dyed material gradually increased with increasing numbers of wash. Also the f(k) values were decreased reversely. During repeated washing, the vagrant dyes were deposited especially on nylon, polyester, cotton of the adjacent multifiber. C. I. Vat Blue 5 displayed lowest color change to repeated washing of the three dyes used.