To provide a tapered gap measure which can be manipulated switchingly to reduce invasion amount into a gap when the gap is large.

A pair of plate-like gap measure main bodies 10, 20 of the same isosceles triangular shape are overlapped each other in a shifted state with respective axes of symmetry X passing vertices agreed. Two link arms 9 of the same length are arranged on the axes of symmetry so that the main bodies 10, 20 can rotate relatively to a position where the axes of symmetry X are parallel to each other. At the same time, one end part of each link arm 9 is pivotally fitted to the main body 10, and the other end part of the arm is pivotally fitted to the other main body 20. A normal gap scale corresponding to a lateral breadth of the main body 20 is indicated on the main body 20 shifted forward while the axes of symmetry X are agreed. The main body 10 shows a scale of a sum of a distance between fit positions of the link arms 9 and the normal gap scale.