This opening-type disposable diaper (1) is provided with: an elastic crotch section (200a) that is formed in an absorbent body positioning region having an absorbent body (40) positioned in a crotch area (25), and is able to stretch in the product longitudinal direction (L) a pair of elastic leg sections (75) that are formed along leg openings (35), and are able to stretch in at least the product longitudinal direction (L) and an elastic waist section (100) that is formed in a rear waistline area (30), and is able to stretch in the product width direction (W). An absorbent body core positioning region (300) surrounded by the elastic crotch section (200a), the elastic leg sections (75) and the elastic waist section (100), and having an absorbent body core (40a) constituting the absorbent body (40) positioned therein, is formed so as not to stretch. The length (L2) of the absorbent body core positioning region (300) in the product longitudinal direction (L) is configured so as to become longer than half of the length (L1) of the elastic crotch section (200a) in the product longitudinal direction (L).
