The disclosed technology generally relates to a tire, and more particularly to a non-pneumatic tire that has handling performance similar to a pneumatic tire, supports the load of a vehicle and improves riding comfort by employing a parametric structure. In one aspect, a non-pneumatic tire includes a tread that comes in contact with the ground, a rim that is connected with an axle, and a spoke unit that functions as a structural support between the rim and the tread, in which the spoke unit is formed by circularly arranging spokes. The spokes have a single closed-loop longitudinal cross-section circumscribed to the rim and around the center of the tire.