PURPOSE: To improve drastically stability in orientation after that, consequently film manufacturing efficiently is improved greatly and a film possessing excellent mechanical and thermal properties are obtained, by feeding a lubricant between a rolled matter and rolls in a rolling process.

CONSTITUTION: A melted and solidified film is biaxially oriented after the same is rolled by allowing the same to pass through between rolls while coating the same with a lubricant at a pressure point under sufficient pressure so that a pressure drop ratio (r) satisfies a formula (t0 is film thickness before rolling and (t) is a film thickness after rolling). Draw ratios of biaxial orientation after rolling are at least three times in a lateral direction and at least 1.1 times in a longitudinal direction. A biaxially oriented film comprised of polyoxymethylene polymer whose principal part of a main chain is constituted substantially of a repeating unit of an oxymethylene group (CH2-0) is manufactured by the above method.