Abstract: The present disclosure provides a functional male underpants comprising: a scrotum bag 10 which fixes a man's scrotum such that the scrotum is inserted from a top thereof and is not in contact with a thigh, and in which a top and bottom thereof are open in such a manner that ventilation is achieved for the scrotum; a first pocket 20 integrally combined with a front of the scrotum bag 10 at an upper portion thereof, so that the scrotum is not in contact with a man's penis; second and third pockets 21,22 integrally combined with left and right sides of the scrotum bag 10 respectively at an upper portion thereof, so that the scrotum and the thigh are not in contact with each other; left and right length-adjustment bands 11, 11a, the left length-adjustment band 11 connecting a left side of the scrotum bag 10 and an inner left side of an underpants body 1 with each other, the right length-adjustment band 11a connecting a right side of the scrotum bag 10 and an inner right side of the underpants body 1 with each ot