Abstract: Disclosed is a strapless backless seamless adhesive brassiere without waterproofing and a manufacturing method thereof, in which an inner layer, an intermediate layer and an outer layer are sequentially laminated, adhered together using an adhesive agent, heat-pressed in a one-piece form, and then cut in a shape of brassiere cups and an adhesive region using ultrasonic waves, after which adhesiveness is applied only to the adhesive region of the brassiere other than brassiere cups to attach the brassiere to the skin of a wearer, wherein the adhesive layer uniformly infiltrates to a depth of about ½ of the thickness of the intermediate layer through the inner layer and is securely fixed using a solidification process through rapid cooling or high-temperature treatment.