A method of producing a TAB tape carrier that can produce a TAB tape carrier in such a way as to prevent undulation at a split end surface thereof and tear of circuit pattern thereat, thereby producing the TAB tape carrier of high reliability with increased efficiency. In the method, an insulating layer is formed on an elongate metal supporting layer by application of resin solution to the metal supporting layer and by drying, first. Then, a plurality of lines of wiring patterns are formed on the insulating layer in a semi-additive process. Thereafter, slit grooves are formed in the metal supporting layer in spaces between adjacent lines of wiring patterns. Then, the insulating layer is split along the slit grooves to divide the continuous sheet into individual strips, thereby producing the TAB tape carriers.