To provide a flange for connecting a pipe to another element which can easily weld connecting parts.

Related to a flange 60 for connecting a pipe 80 to another element, the flange 60 comprises: a flange body 61 having a face 62 at a near side for attachment to the other element and a face 63 at an opposing remote side; a center hole 70 being the center hole 70 in the flange body 61 in which the center hole 70 is decided in size and formed for receiving and supporting an end portion 81 of the pipe 80 which is fixed to the flange 60 and connectable, and also in which the center hole 70 is opened at the face 62 at the near side and the face 63 at the remote side; and a welding recess which is used as a diameter-expanded portion 71' of the center hole 70, opened at the face 62 at the near side, and formed so as to provide a welding space between the end portion 81 of the pipe 80 and the flange 60.