Abstract: The present invention relates to acrylic fibers each having a Y-type cross section which consist of an acrylic polymer constituted of at least 50% by weight of acrylonitrile, characterized in that the Y-type cross section is constructed substantially of three rectangles and when the thickness values of the middle part, innermost part, and outermost part of each component rectangle are represented by d.sub.0, d.sub.1, and d.sub.2, respectively, the ratios of d.sub.1 /d.sub.0 and d.sub.2 /d.sub.0 are each in the range of 0.95 to 1.05, and a process for producing the same comprising discharging an organic solvent solution which contains an acrylic polymer constituted of at least 50% by weight of acrylonitrile, dissolved at a concentration of 22 to 30% by weight, and has a viscosity of 200 to 500 poises, through spinneret holes each having a Y-type cross section constructed substantially of three rectangles, into a coagulating liuqid composed of an organic solvent and water at a spinning draft of 1.1 to 1.