A catheter comprising: a catheter shaft in which a lumen is formed, the catheter including a proximal portion; a hub in which a hub lumen communicating with the lumen is formed, the lumen defining an inner peripheral surface of the catheter shaft, the hub being provided on a proximal end portion of the catheter shaft; the catheter shaft including a shaft inner surface inclined portion which is formed on the inner peripheral surface of the proximal portion of the catheter shaft, the shaft inner surface inclined portion possessing an inner diameter increasing toward a proximal direction such that the shaft inner surface inclined portion forms an inclination angle (β) with respect to a central axis of the catheter; the hub including a first hub inner surface inclined portion that is continuous and smooth from the shaft inner surface inclined portion in a non-stepwise manner and that is inclined at an inclination angle with respect to the central axis of the catheter that is the same as the inclination angle (β) of the shaft inner surface inclined portion; the hub also including a second hub inner surface inclined portion on a proximal side of the first hub inner surface inclined portion, the second hub inner surface inclined portion possessing an inner diameter which increases toward the proximal direction such that the second hub inner surface inclined portion forms an inclination angle (α) with respect to the central axis of the catheter that is different from the inclination angle of the first hub inner surface inclined portion; and the hub not covering the inner peripheral surface of the catheter shaft in an interlock portion in which the catheter shaft and the hub are interlocked together at a position of an inclined portion, where the inner peripheral surface is uncovered or exposed. a catheter shaft in which a lumen is formed, the catheter including a proximal portion; a hub in which a hub lumen communicating with the lumen is formed, the lumen defining an inner peripheral surface of the catheter shaft, the hub being provided on a proximal end portion of the catheter shaft; the catheter shaft including a shaft inner surface inclined portion which is formed on the inner peripheral surface of the proximal portion of the catheter shaft, the shaft inner surface inclined portion possessing an inner diameter increasing toward a proximal direction such that the shaft inner surface inclined portion forms an inclination angle (β) with respect to a central axis of the catheter; the hub including a first hub inner surface inclined portion that is continuous and smooth from the shaft inner surface inclined portion in a non-stepwise manner and that is inclined at an inclination angle with respect to the central axis of the catheter that is the same as the inclination angle (β) of the shaft inner surface inclined portion; the hub also including a second hub inner surface inclined portion on a proximal side of the first hub inner surface inclined portion, the second hub inner surface inclined portion possessing an inner diameter which increases toward the proximal direction such that the second hub inner surface inclined portion forms an inclination angle (α) with respect to the central axis of the catheter that is different from the inclination angle of the first hub inner surface inclined portion; and the hub not covering the inner peripheral surface of the catheter shaft in an interlock portion in which the catheter shaft and the hub are interlocked together at a position of an inclined portion, where the inner peripheral surface is uncovered or exposed.