During his two-and-a-half-hour tour of the exhibition, Imam Khamenei visited a number of pavilions as publishers provided information about their latest publishing activities.
Iranian Culture and Islamic Guidance Minister Ali Jannati accompanied the Supreme Leader in the visit.
The 28th edition of Tehran International Book Fair kicked off on Tuesday in a 120,000 square meter venue at Tehran's Grand Prayer Grounds, and will continue until May 16.
Over 2800 publishers from Iran and several other countries have presented more than 450,000 of their latest publications at the event.
With a 20-percent increase in the number of books exhibited in the fair, 300,000 Iranian books and 160,000 non-Iranian books are presented this year.
Tehran International Book Fair is annually held as a social and cultural phenomenon with book displays, panel discussions and publishing deals.
The fair is considered as one of the most significant events of its kind in Asia and the Middle East and a significant venue for publishers and book lovers to exchange opinions and experiences.