A rotating body load measuring device for detecting a force acting on a columnar load wheel that is formed in a columnar shape and configured to rotate around a central axis of a shaft body protruding from a center of an end face of the load wheel, in a state where a main load is applied to the columnar load wheel in a main load direction that is one direction in a radial direction of the load wheel, the rotating body load measuring device being a tire uniformity machine and comprising: a tire support part for supporting a tire that is a test object so as to be rotatable around a tire central axis, the columnar load wheel is supported to be rotatable around an axis parallel to the tire central axis, so as to come into contact with a peripheral surface of the tire, a rotation drive portion configured for rotationally driving either of the tire or the load wheel, and a load cell having a measurement center and being capable of measuring forces acting in at least three directions with reference to the measurement center, wherein the load cell is disposed such that the measurement center and the central axis overlap when viewed in the main load direction, and is connected to the shaft body; wherein the rotating body load measuring device is configured to measure non-uniformity of the tire, based on a force that is measured in the load cell; characterized in that the rotating body load measuring device further comprises: a fixing jig which is mounted on the shaft body so as to be rotatable around a mounting shaft orthogonal to the central axis, and to which the load cell is fixed; wherein one of the shaft body and the fixing jig includes a pair of first mounting portions disposed with the central axis interposed therebetween, and the other of the shaft body and the fixing jig includes a second mounting portion that is disposed in a plane that includes the central axis, between the pair of first mounting portions, and is mounted to the pair of first mounting portions to be rotatable around the mounting shaft. a tire support part for supporting a tire that is a test object so as to be rotatable around a tire central axis, the columnar load wheel is supported to be rotatable around an axis parallel to the tire central axis, so as to come into contact with a peripheral surface of the tire, a rotation drive portion configured for rotationally driving either of the tire or the load wheel, and a load cell having a measurement center and being capable of measuring forces acting in at least three directions with reference to the measurement center, wherein the load cell is disposed such that the measurement center and the central axis overlap when viewed in the main load direction, and is connected to the shaft body; wherein the rotating body load measuring device is configured to measure non-uniformity of the tire, based on a force that is measured in the load cell; characterized in that the rotating body load measuring device further comprises: a fixing jig which is mounted on the shaft body so as to be rotatable around a mounting shaft orthogonal to the central axis, and to which the load cell is fixed; wherein one of the shaft body and the fixing jig includes a pair of first mounting portions disposed with the central axis interposed therebetween, and the other of the shaft body and the fixing jig includes a second mounting portion that is disposed in a plane that includes the central axis, between the pair of first mounting portions, and is mounted to the pair of first mounting portions to be rotatable around the mounting shaft. a fixing jig which is mounted on the shaft body so as to be rotatable around a mounting shaft orthogonal to the central axis, and to which the load cell is fixed; wherein one of the shaft body and the fixing jig includes a pair of first mounting portions disposed with the central axis interposed therebetween, and the other of the shaft body and the fixing jig includes a second mounting portion that is disposed in a plane that includes the central axis, between the pair of first mounting portions, and is mounted to the pair of first mounting portions to be rotatable around the mounting shaft.