To simply store such a document as a written guarantee in an instruction manual.

In the instruction manual 1 for an electronic instrument whose back part 2 is bound spreadably, by binding an upper edge part 5, a lower edge part 6 and a side edge part 9 of the back cover 3 being the outside of this instruction manual 1 and of the paper part 4 overlapped with this back cover 3, a document storing part 7 is formed between the back cover 3 and the paper part 4. A document inserting opening 12 is formed on the back cover 3. It is possible thereby to simply store such the document as the written guarantee 11 in the document storing part 7 from the document inserting opening 12 without opening the instruction manual 1.