The present invention aims at providing a trunks type diaper which allows a good feeling of wearing around both thighs when wearing the diaper, is easily worn and undressed, and has high leakage prevention.In a situation where the diaper is developed, a first thigh elastic member (15a) extends substantially linearly from a left edge (7a1) of the front main section to a right edge (7b1) of the front main section via a crotch section (6) front edge a second thigh elastic member (15b) also extends substantially linearly from a left edge (7a2) of the rear main section to a right edge (7b2) of the rear main section via a crotch section (6) rear edge. As a result, in the bottom of the diaper in a situation where the left and right edges (7a1, 7b1, 7a2, 7b2) of the front and rear main sections (2, 3) are joined, the first and second thigh elastic members are arranged to surround the left and right thigh openings (5a, 5b) as one pair.