A seat pad (10) is formed from a foamed molded body. A passenger contact surface (11) which, in a plan view of the seat pad (10), is formed in the shape of a rectangle that is long in the lengthwise direction (X) and short in the widthwise direction (Y), is provided. The passenger contact surface (10) comprises a main pressure-receiving area (11a) with which the buttocks or the waist of a passenger come into contact, and a subsidiary pressure-receiving area (11b) that is adjacent to the main pressure-receiving area (11a) in the lengthwise direction (X). The passenger contact surface (11) is provided with partitioning grooves (15) that extend in the lengthwise direction (X) and that are arranged across the main pressure-receiving area (11a) and the subsidiary pressure-receiving area (11b). The partitioning grooves (15) are arranged so as to lie parallel to each other in the widthwise direction (Y). Additional grooves (16) are formed on the bottom surfaces of the partitioning grooves (15). In the partitioning grooves (15), the average volume, which is the ratio of the volume of the additional grooves (16) per unit area of the bottom surfaces of the partitioning grooves (15), is smaller in a first section (15a) located in the main pressure-receiving area (11a) than in a second section (15b) located in the subsidiary pressure-receiving area (11b).