An optical fiber sheet 10 includes an optical fiber 11 and a wire 12 that are arranged between a first sheet and a second sheet. The optical fiber 11 is a multi-mode optical fiber having a core of silica glass to which a refractive index adjuster is added, has a numerical aperture equal to or less than 0.30 and a flexural rigidity equal to or less than 0.50 N·mm2, and is bent to be arranged between the first sheet and the second sheet. The wire 12 intersects the optical fiber 11 between the first sheet and the second sheet.
