An external form measuring apparatus for measuring an external form of an object comprising: a first chuck configured to rotatably grip a first end portion of the object to be measured; a second chuck configured to rotatably grip a second end portion of the object to be measured; a first calibration plate fixed to the first chuck, the first calibration plate having a first insertion hole to which the first end portion is inserted, the first calibration plate being formed in round plate shape; a second calibration plate fixed to the second chuck, the second calibration plate having a second insertion hole to which the second end portion is inserted, the second calibration plate being formed in round plate shape; a laser displacement meter arranged to a side of the object to be measured, the laser displacement meter configured to move along a rotation axis of the first chuck, the laser displacement meter configured to measure positions of the object to be measured, the first calibration plate and the second calibration plate rotating about the rotation axis; an optical axis calibration value calculation unit configured to calculate first optical axis calibration value and second optical axis calibration value showing an interval between the rotation axis and an optical axis of the laser displacement meter defined by an irradiated laser beam, wherein the interval extends in a vertical direction to the optical axis, based on measured value data (L 1, L 2, L 3, L 01, L 11, L 13, L 20) of each of the first and second calibration plates (17a, 17b) and design value data (Lo) of each of the first and second calibration plates (17a, 17b) which are measured by the laser displacement meter; and an external form measuring unit configured to measure an external form of the object to be measured by calibrating the measured value data (L 1, L 2, L 3, L 01, L 11, L 13, L 20) of the object to be measured by the laser displacement meter based on the first optical axis calibration value and the second optical axis calibration value; a center (Qa) of the first insertion hole being away from a center (Pa) of the first calibration plate, and a center of the second insertion hole being away from a center of the second calibration plate. a first chuck configured to rotatably grip a first end portion of the object to be measured; a second chuck configured to rotatably grip a second end portion of the object to be measured; a first calibration plate fixed to the first chuck, the first calibration plate having a first insertion hole to which the first end portion is inserted, the first calibration plate being formed in round plate shape; a second calibration plate fixed to the second chuck, the second calibration plate having a second insertion hole to which the second end portion is inserted, the second calibration plate being formed in round plate shape; a laser displacement meter arranged to a side of the object to be measured, the laser displacement meter configured to move along a rotation axis of the first chuck, the laser displacement meter configured to measure positions of the object to be measured, the first calibration plate and the second calibration plate rotating about the rotation axis; an optical axis calibration value calculation unit configured to calculate first optical axis calibration value and second optical axis calibration value showing an interval between the rotation axis and an optical axis of the laser displacement meter defined by an irradiated laser beam, wherein the interval extends in a vertical direction to the optical axis, based on measured value data (L 1, L 2, L 3, L 01, L 11, L 13, L 20) of each of the first and second calibration plates (17a, 17b) and design value data (Lo) of each of the first and second calibration plates (17a, 17b) which are measured by the laser displacement meter; and an external form measuring unit configured to measure an external form of the object to be measured by calibrating the measured value data (L 1, L 2, L 3, L 01, L 11, L 13, L 20) of the object to be measured by the laser displacement meter based on the first optical axis calibration value and the second optical axis calibration value; a center (Qa) of the first insertion hole being away from a center (Pa) of the first calibration plate, and a center of the second insertion hole being away from a center of the second calibration plate.