Disclosed is an aroma-diffusing cartridge for a vehicle wherein the structures of the cartridge and a carrier of an aroma are so optimized that the capacity of the carrier for carrying the aroma may become excellent together with stable and continuous performance of diffusing the aroma. An aroma-diffusing cartridge for a vehicle includes: a cartridge body having one side formed with a pair of air holes for receiving and discharging air, and an internal space for circulating the received air; and at least two carriers put in the cartridge body with different duration of keeping an aroma. Thus, the capacity of the carriers for carrying an aroma is excellent together with stable and continuous performance of diffusing the aroma in a limited space, so that the air in the vehicle may be kept agreeable for a long time.