This angle measurement method is a method of measuring an angle of a variable vane of an axial flow fluid machine including a vane main body which is disposed inside of a casing, and an arm which is disposed outside of the casing and rotates integrally with the vane main body, and includes: a jig mounting step of mounting a measurement jig configured to measure an angle of the vane main body on the arm in a fixed posture in a rotation direction of the arm; and a measurement step of measuring a relative angle between a predetermined angle reference surface intersecting the rotation direction of the arm and at least a portion of the measurement jig.