In a turbine housing 12 of a turbocharger 10A of a twin-scroll type, a scroll-shaped passage is separated into a front scroll passage 42 and a rear scroll passage 44 by a partition wall 40. A front wall 50 and a root part 40b of the partition wall 40 curve toward a front side to secure cross-sectional areas a1, a2, a3 . . . and b1, b2, b3 . . . . The scroll passages 42, 44 are formed to have equal cross-sectional areas, a tip part 40a of the partition wall 40 is arranged perpendicular to the turbine rotor blade 26 and the scroll passages 42, 44 are symmetrical near the tip part 40a about an axis X so as to eliminate the flow rate difference.