Electronic book system and its contents display method

The invention relates to an electronic book system (a contents display method) that functionally or efficiently displays information related to reading or advertisement in a small display area on a display of a portable reading terminal, the portable reading terminal receives digitized book contents and digitized related information proper to the contents via the Internet and the related information is displayed together with the book contents on the portable reading terminal by operating a button of the portable reading terminal or operator guidance on the display screen. The electronic book system is composed of a provider 1 provided with a book contents server 2 that stores digitized book contents and the related information, a bookshelf server 3 that temporarily deposits a book from a user and a management server 4 that manages the personal information of users and the portable reading terminal 6 provided with CPU, a screen display and a nonvolatile storage including a book contents storage, a reading situation manager and a viewer.