Measurement method

A measurement method, comprising:

• a step of preparing an object to be measured having a first surface to be measured and a second surface to be measured that are opposite each other, and a reference object having a first reference surface and a second reference surface that are opposite each other;
• and
• a step of measuring the object to be measured and the reference object by a first measurement unit and a second measurement unit supported by a frame-like supporting member, wherein:
• the first measurement unit has a first displacement meter and a second displacement meter disposed to face each other in a first direction;
• the second measurement unit has a third displacement meter and a fourth displacement meter disposed to face each other in the first direction;
• the first measurement unit and the second measurement unit are supported by the frame-like supporting member in a state of being arranged side by side in a second direction orthogonal to the first direction;
• the step of preparing the object to be measured and the reference object includes disposing the object to be measured such that the first surface to be measured faces the first displacement meter and the second surface to be measured faces the second displacement meter and disposing the reference object such that the first reference surface faces the third displacement meter and the second reference surface faces the fourth displacement meter;
• the step of measuring the object to be measured and the reference object includes a step of measuring a distance from the first surface to be measured and a distance from the second surface to be measured by the first displacement meter and the second displacement meter, respectively, and measuring a distance from the first reference surface and a distance from the second reference surface by the third displacement meter and the fourth displacement meter, respectively;
• and
• a member including a first frame portion that supports the first displacement meter and the third displacement meter on one side in the first direction, a second frame portion that supports the second displacement meter and the fourth displacement meter on the other side in the first direction, a third frame portion that connects end portions of the first frame portion and the second frame portion to each other on one side in the second direction, and a fourth frame portion that connects end portions of the first frame portion and the second frame portion to each other on the other side in the second direction is used as the frame-like supporting member.