To provide a base sheet for optical sheet which is superior in anti-sticking property, includes high total light transmittance, can effectively suppress interference phenomenon and luminance irregularity and includes high economical efficiency and thin film characteristic.

The base sheet for optical sheet includes a transparent base film and an anti-sticking layer laminated on one side surface of the base film, wherein the anti-sticking layer includes fillers and a resin binder, an average thickness of a flat part of the anti-sticking layer is 50 nm to 150 nm and an average particle size of the fillers is 70 nm to 200 nm. Preferably, the average particle diameter of the fillers is set to be larger than the average thickness of the flat part of the anti-sticking layer. Preferably, a content of the fillers in the anti-sticking layer is set to be 20 mass% to 50 mass%. The binder polymer includes preferably a three-dimensional crosslinking structure.