PURPOSE: To attain bright, easily visible and excellent picture feeling by arranging such a picture quality improving film between a liquid crystal display element and a prism sheet, that consists essentially of a colorless, transparent plastic, and controlling its full light transmissivity to a specific value and diffusion half value angle of vertical incident light to the range of a specific angle.

CONSTITUTION: The picture quality improving film 21 is arranged between a liquid crystal display element 11 and a prism sheet 18 and consists eassentially of the colorless, transparent plastic. The full light transmissivity in the picture qunality improving film 21 is ≥80% and the diffusion half value angle of the vertical incident light is 5-15°. When the full light transmissivity is under 80°, light utilization efficiency is decreased. And the diffusion half value and in diffusing power is preferably 8-20°, in the case of being under 5°, light emission is not converted into a desired state and the picture feeling is not improved and in the case of exceeding 15°, the quantity of light is decreased. And the purpose is attained by inserting the picture improving film 21 between the prism sheet 18 and the liquid crystal display element 11.