PURPOSE: To provide a seat mat excellent in comfortableness in use by dividing a bag formed by an air-permeable base into plural areas, and filling the respective divided areas with carbide powder.

CONSTITUTION: Each charcoal pad 12 is formed by enclosing urethane foam 16 and activated carbon 17 in a bag 15 having a substantially semicircular section. As a raw material for the bag 15, the raw material to which a fine porous film is stuck is used. A mattress 10 is formed by arranging plural plane square charcoal pads 12 side by side, the weight at the time of lying is dispersed and borne by the respective charcoal mats 12, and activated carbon 17 is lowered, following the movement of the urethane foam 16 not to escape in the lateral direction. If the lying time is long, a contact surface is dispersed so as to remarkably reduce the generation of a bedsore. Furthermore, as each charcoal pad 12 is divided into plural parts, the pad can softly fit the complicated recessed and projecting parts of the body so as to enable optimum load sharing. Especially in the case of an always lying old person where load is liable to be applied only to a specified part, only the charcoal pad 12 which reaches the limit of use can be replaced so as to reduce the maintenance cost.