A misalignment determining device comprising: a tubular case having a through hole extending along an axis; a dial gauge fixed to the case with a graduation scale portion thereof being exposed from the case and configured to determine a change amount of a distance; a holder portion inserted to the through hole and rotatable relative to the case coaxially with the axis; a support portion that supports the holder portion on a base end side of the holder portion; a pivotal portion pivotable as being held to a leading end side of the holder portion; a lever member extending along an intersecting direction intersecting the axial direction at a position which is on the leading end side and which also is on a side closer to the base end side than the pivotal portion is, the lever member being held to the holder portion in such a manner to be pivotable about a pivot axis which is in a direction perpendicular to both the axial direction and the intersecting direction, a pivot amount of the pivotal portion being transmitted to the lever member; and a slide member accommodated in the case at a position on more base end side than the lever member and configured to come into contact with the lever member to be movable along the axial direction; wherein the slide member is placed in contact with a stylus of the dial gauge; and as the pivotal portion and the lever member are rotated in synchronism with rotation of the holder portion, a pivot amount of the pivotal portion is transmitted to the slide member via the lever member; and based on a movement amount of the slide member along the axial direction, the dial gauge determines the pivot amount; characterized in that the misalignment determining device further comprises a unit amount converter member fixed to the pivotal portion at a position between the pivotal portion and the lever member and configured to change a unit movement amount of the slide member relative to a unit pivot amount of the pivotal portion. a tubular case having a through hole extending along an axis; a dial gauge fixed to the case with a graduation scale portion thereof being exposed from the case and configured to determine a change amount of a distance; a holder portion inserted to the through hole and rotatable relative to the case coaxially with the axis; a support portion that supports the holder portion on a base end side of the holder portion; a pivotal portion pivotable as being held to a leading end side of the holder portion; a lever member extending along an intersecting direction intersecting the axial direction at a position which is on the leading end side and which also is on a side closer to the base end side than the pivotal portion is, the lever member being held to the holder portion in such a manner to be pivotable about a pivot axis which is in a direction perpendicular to both the axial direction and the intersecting direction, a pivot amount of the pivotal portion being transmitted to the lever member; and a slide member accommodated in the case at a position on more base end side than the lever member and configured to come into contact with the lever member to be movable along the axial direction; wherein the slide member is placed in contact with a stylus of the dial gauge; and as the pivotal portion and the lever member are rotated in synchronism with rotation of the holder portion, a pivot amount of the pivotal portion is transmitted to the slide member via the lever member; and based on a movement amount of the slide member along the axial direction, the dial gauge determines the pivot amount; characterized in that the misalignment determining device further comprises a unit amount converter member fixed to the pivotal portion at a position between the pivotal portion and the lever member and configured to change a unit movement amount of the slide member relative to a unit pivot amount of the pivotal portion.