In order to switch to a light source with a light amount corresponding to the type of original from among a plurality of light sources in a simplified structure without using a specific switching mechanism in reading a transmissive original with a photoelectric sensor while moving, there are provided a platen on which an original is mounted, a line sensor that performs photoelectric conversion on light from the original on the platen, a first carriage that moves along the platen and guides the light from the original to the line sensor, a first housing that stores and supports the first carriage to be movable along the platen, first driving means for moving the first carriage, a second carriage provided with a plurality of rod-shaped light-source lamps that applies light to the original, a second housing that stores and supports the second carriage to be movable along the platen and covers the platen, second driving means for moving the second carriage, and control means for controlling the first driving means, the second driving means and lighting of the plurality of light-source lamps, where the plurality of light-source lamps is spaced in parallel with one another in the moving direction of the second carriage, and due to a signal from means for selecting a single light-source lamp from the plurality of light-source lamps corresponding to the type of the original, the control means controls to move the first carriage from a standby position to a predetermined position, further move the second carriage from a standby position by an amount of movement set corresponding to the selected light-source lamp to position in the predetermined position, and then, move the first carriage and the second carriage at the same speed from the predetermined position to a reading start position of the original.