Disclosed are liquid crystal polyester fibers, which have a peak half-width of 15° C. or greater at an endothermic peak (Tm1) observed by differential calorimetry under a temperature elevation of 20° C./minute from 50° C., polystyrene equivalent weight average molecular weight of 250,000 or more and 2,000,000 or less, and a variable waveform of less than 10% in terms of the half inert diagram mass waveform determined by a Uster yarn irregularity tester. Also disclosed is a method for producing liquid crystal polyester fibers, wherein liquid crystal polyester fibers are formed into a package, the fibers are then subjected to solid-phase polymerization, and the solid-phase polymerized liquid crystal polyester fibers are unrolled from the package and successively heat treated without being once taken up. The heat treatment temperature is controlled at a temperature of the endothermic peak temperature (Tm1) of the solid-phase polymerized liquid crystal polyester fibers+60° C. or higher, and the speeds of the fibers before and after heat treatment are regulated, respectively, by first and second rollers.