PROBLEM TO BE SOLVED: To provide an open-type disposable diaper that can be easily and correctly put on a wearer.SOLUTION: An absorbent article 1 includes a crotch expansion part 200a formed within an absorber arranged region with an absorber 40 arranged in a crotch region 25, and expansible in a longitudinal direction L of a product a pair of leg expansion parts 75 formed along a leg opening 35 and expansible in at least the longitudinal direction L of the product and a waist expansion part 100 formed in a rear waist region 30 and expansible in a width direction W of the product. An absorber core arranged region 300 surrounded by the crotch expansion part 200a, the leg expansion parts 75 and the waist expansion part 100 and having an absorber core 40a arranged therein to compose the absorber 40, is formed not to expand/contract, and the length L2 of the absorber core arranged region 300 in the longitudinal direction L of the product is formed to be longer than the half of the length L1 of the crotch expansion part 200a in the longitudinal direction L of the product.
