To provide a pipe clamp device which prevents occurrence of a step extending in the axial direction of a pipe and located between upper and lower liners by pressing force in flaring, and to provide a flaring device using the same.

A projection 11 is provided on a mating surface of a lower clamp member 1b, an opening 12 for receiving the projection 11 is provided in a mating surface of an upper clamp member 1a, the projection 11 has a flat surface 13a perpendicular to the axis of a pipe 4, and the flat surface 13a is provided to be flush with a contact surface 13b making contact with a stepped surface 2c of a lower liner 3b of the lower clamp member 1b. Pressing force in flaring of the clamped pipe causes a stepped surface 2c of an upper liner 3a to be flush with and engage the stepped surface 2c of the lower liner 3b, and this prevents occurrence of a step extending in the axial direction of the pipe and located between the upper and lower liners 3a, 3b.