There is a film image information reading apparatus called a film scanner. This apparatus comprises: a lighting optical system to illuminate a film document; a photoelectric conversion element, such as a CCD to convert the image information of the film document into the electric signal; and an adjusting circuit to adjust the output of the photoelectrical conversion element such that a predetermined density of the film document is output as an output of almost the saturation level of that element. The predetermined density is the color density of the base color of a negative film. The adjusting circuit may control the charge storage period, gain, or output level of the photoelectric conversion element. With this apparatus, the positive image can be easily derived by reversing the negative image without considering the base color of the negative film and the image signal of a high quality can be obtained.