Size headwear and manufacturing method thereof

A manufacturing method of a size headwear including a head covering portion put on a head and a size tape member disposed on a lower portion of the head covering portion, the head covering portion has a single circumferential length, includes forming a single set of patterns for forming a single set of pieces of the head covering portion; cutting a fabric into the single set of pieces according to the single set of patterns; sewing the cut pieces with each other and connecting the size tape member along a circumferential direction on a lower portion of the sewed pieces to form a raw size headwear; and putting a raw size headwear on a plurality of thermoforming apparatuses to thermoform a size headwear, wherein the thermoforming apparatuses have the respective different sizes. The size headwear thermoformed in this manner may be inexpensively and easily produced and maintain a predetermined stereoscopic shape due to stiffness so that it may improve an esthetic sense without doing the ironing.