Fixing jig and fixing method for fixing sensor

A fixing jig for fixing a sensor to a surface of a pipe,

• wherein the fixing jig comprises:
• at least one buffer material;
• a band member attached to the pipe along the surface;
• and
• an adjustment part forming the band member into a ring shape by combining a first end portion including one end of the band member and a second end portion including another end of the band member, and configured to adjust a diameter of the ring shape, and
• wherein the at least one buffer material has two slits formed therein at an interval from each other, the first end portion of the band member is passed through one of the two slits from a first surface which is one surface of the at least one buffer material, the first end portion of the band member is inserted into the other of the two slits from a second surface which is another surface of the at least one buffer material, and in a state in which the first end portion and the second end portion of the band member are positioned on a side of the first surface, the at least one buffer material is attached to the band member.