The ministry said in a statement that an improvised explosive devise went off as the bus, carrying 14 Vietnamese tourists, was passing Marioutiya Street in Giza on Sunday about 6:15 pm (1645 GMT).
The explosion also injured 11 other people, the statement added.
Security services were immediately dispatched to the incident site, the ministry said, adding an investigation is underway.
Over the past few years, terrorists have been carrying out anti-government activities and fatal attacks, taking advantage of the turmoil in Egypt that erupted after the country’s first democratically-elected president, Mohamed Morsi, was ousted in a military coup in July 2013.
The Velayat Sinai group, which is affiliated with Daesh, has claimed responsibility for most of the assaults. The group later expanded its attacks to target members of Egypt’s Coptic Christian community as well as foreigners visiting the country, prompting Cairo to widen a controversial crackdown, which critics say has mostly targeted dissidents.