Sheet measuring apparatus and image forming apparatus

An image forming apparatus comprising:

• a first rotating member that includes a first peripheral surface portion that contacts a transported sheet, the first rotating member being rotated as a result of transporting of the sheet;
• a second rotating member that includes a second peripheral surface portion that is made of a material different from a material of the first peripheral surface portion, the second peripheral surface contacting the first peripheral surface portion and not contacting the sheet, the second rotating member rotating as the first rotating member rotates;
• a first rotation amount detecting unit that detects a first rotation amount that is a rotation amount of the first rotating member;
• a second rotation amount detecting unit that detects a second rotation amount that is a rotation amount of the second rotating member, the second rotation amount being used for a calculation related to the transported sheet;
• an image forming unit that forms an image on the sheet on the basis of a result of the calculation related to the transported sheet;
• and
• a fault detecting unit that detects a fault that has occurred in the first rotating member on the basis of the first rotation amount and the second rotation amount.