A catheter includes an inner layer, a coil body covering the inner layer, and an outer layer covering the coil body. The coil body includes a plurality of element wires (thin wires and thick wires). The thick wires of the coil body are ground so that the cross-sectional shape of the thick wires is semicircular, and an inner diameter and an outer diameter of the coil body are substantially constant in a part in which the thick wires are ground. It is thus possible to prevent occurrence of unevenness on an outer peripheral surface or an inner peripheral surface of the catheter. Furthermore, when the catheter is bent, the thin wires move along the circular arc portion of the thick wires, which allows the catheter to bend a relatively large amount.