TOKYO — Japan is renowned for its robots and bullet trains, and has some of the world’s fastest broadband networks. But it also remains firmly wedded to a pre-Internet technology — the fax machine — that in most other developed nations has joined answering machines, eight-tracks and cassette tapes in the dustbin of outmoded technologies.

Last year alone, Japanese households bought 1.7 million of the old-style fax machines, which print documents on slick, glossy paper spooled in the back. In the United States, the device has become such an artifact that the Smithsonian is adding two machines to its collection, technology historians said.

“The fax was such a success here that it has proven hard to replace,” said Kenichi Shibata, a manager at NTT Communications, which led development of the technology in the 1970s. “It has grown unusually deep roots into Japanese society.”

The Japanese government’s Cabinet Office said that almost 100 percent of business offices and 45 percent of private homes had a fax machine as of 2011.