A method and apparatus for using multiple numerologies in a wireless communication system is provided. A user equipment (UE), specifically UE supporting ultra-reliable low-latency communication (URLLC), uses a first numerology in a first numerology resource unit group (NRG) with a reference subcarrier spacing, switches from the first numerology to a second numerology, and uses the second numerology in a second NRG with a specific subcarrier spacing different from the reference subcarrier spacing. The first NRG is a set of frequency and time resources based on the first numerology, and the second NRG is a set of frequency and time resources based on the second numerology.