To prevent an image from being blurred when an operator slightly floats a device body in error at the time of reading out an image by moving a handy scanner on the surface of an original.

A reading unit 30 constituted of integrating an image reading part for reading out an image, converting the read image into an electric signal and outputting the electric signal and a roller 21 arranged so as to be pressed in contact with the surface of the original to detect sub-scanning quantity has an oscillation mechanism for optionally oscillating a case constituting an outer wall for a device. A compression spring 51 applies force for mutually separating the unit 30 and the case 41 to them and the unit 30 is held at a certain position by a stopper of the case 41. When the lower end face of the case 41 is pressed until contact with the surface of the original, the unit 30 is pressed into contact with the surface of the original by the compression force of the spring 51.