A resonator for a vehicle, which reduces intake noise by using a resonance chamber for frequency tuning, includes an outer pipe having a first outer pipe with an inlet for introducing external air and a second outer pipe with an outlet for discharging the air introduced into the inlet to outside, an inner pipe disposed inside the outer pipe and having a plurality of slits for giving a passage of air, and an expansion pipe inserted between the outer pipe and the inner pipe to partition a space between the outer pipe and the inner pipe into a plurality of spaces and thus partition the resonance chamber into a plurality of regions.