A substrate for an optical disc is disclosed, which comprises a transparent hydrocarbon resin having a softening point of not less than 100.degree. C., the surface thereof having been contact treated with a fluorine-containing gas so that the treated surface has a contact angle with water of not more than 90.degree. and the weight gain due to the treatment does not exceed 1% by weight. The substrate exhibits excellent adhesion to a recording layer formed thereon and excellent heat resistance.