PURPOSE: To improve surface properties of a fine cell-containing film, particularly smoothness and bonding properties by laminating a polyester film of density larger than the specific value on one or both surfaces of a polyester film containing a number of fine, closed cells and having density in the specific range.

CONSTITUTION: A film layer (layer B) almost not containing any fine, closed cells is laminated on one or both surfaces of a film layer (layer A) containing a number of fine, closed cells. It is essential that the density of layer A is in the range of 0.40-1.30g/cm3, preferably in the range of 0.50-1.20g/cm3. Also, the density of layer B should be larger than 1.30g/cm3, preferably in the range of 1.35-1.50g/cm3. When the density of layer A is beyond 1.30g/cm3, the content of closed cells is small and improving effect to slack aging generated by the own weight of film is almost not recognized, with is not preferred, while, on the other hand, when 0.40g/cm3 or less, the mechanical strength of film is remarkably lowered. Also, when the density of layer B is less than 1.30g/cm3, the smoothness of the film surface is worsened.