The liquid permeability and liquid diffusion of absorbent body is enhanced. (i) A belt-like main sheet formed of a non-woven fabric sheet constituting at least part of a first main surface is conveyed in a longitudinal direction of the main sheet； (ii) a slit is formed in the non-woven fabric sheet at a first position on a conveying path； (iii) at a second position, particulate matter absorbing and retaining liquid is dispersed into the first main surface, in such a way that the particulate matter is held in the non-woven fabric sheet； and (iv) at a third position, a covering sheet which prevents passage of the particulate matter is overlaid on the first main surface. At the second position, the non-woven fabric sheet includes a bulky structure which constitutes at least part of the first main surface and which has voids allowing the particulate matter to enter.
