A side part structure of a vehicle includes a side door and a second seal member. The side door includes a lower end edge which substantially overlaps a wheel arch. The second seal member is configured to seal a gap between a wheel house and the side door. The side door includes a door garnish which faces an outer edge of the wheel house. The second seal member includes an installation base member and a lip integrally formed with the installation base member. The installation base member is configured to operably couple to the outer edge of the wheel house. The lip has a substantially tongue-shaped cross section in a width direction of the vehicle, and makes contact with the door garnish. The lip extends toward an outside in the width direction of the vehicle from a part on an outer side in a radial direction of the installation base member.