To easily process a concave groove, properly form the concave groove, not worsen fittability, and improve diffusion of body fluid. A method of manufacturing an absorbent article in which an absorbent body (4) is provided between a liquid permeable topsheet (3) and a backsheet (2), an absorbent body concave portion (20), which is a concave groove or a slit, being formed at a skin-contacting side including a body fluid expelling area (H) along a longitudinal direction of the absorbent body without using compression, and an embossed portion (21) being formed in the absorbent body concave portion (20) along the absorbent body concave portion (20) by embossing from a top surface side of the liquid permeable topsheet. The method includes a first step of forming the absorbent body (4) provided with the absorbent body concave portion (20)； a second step of forming core embosses (23) at least on both sides of the absorbent body concave portion (20) by compressing the absorbent body from the skin-contacting side of the absorbent body (4)； and a third step of stacking the liquid permeable topsheet (3) on a top surface side of the absorbent body (4) and forming the embossed portion (21).
