A document-reading device has a document-transporting mechanism that has a pick-up roller (R1) etc. and a document- reading mechanism that has a light source unit (6) etc. and reads an image of a document transported by the document-transporting mechanism. Operation of reading a surface (P1a) to be read of the document (P1) by the document-reading mechanism is continued when double transportation occurs in transporting a document (P1) to be read, or another document (P2) is additionally transported together with the document (P1) to be read, and simultaneously when the another document (P2) additionally transported is not positioned between the document (P1) to be read and the light source unit (6) (that is, the another document (P2) does not interrupt the surface (P1a) to be read of the document (P1) to be read).