The robot was designed to be a companion for astronauts to stop them from getting lonely while in space.
Officials at the Japan Aerospace Exploration Agency said the H2B rocket, carrying food, water and other supplies, lifted off from the island of Tanegashima today.
Included in the cargo is a small robot named Kirobo, which will serve as a companion for Japanese astronaut Koichi Wakata who will join the crew later this year.
Kirobo was put through a series of zero-gravity and other safety tests before it was deemed ready for flight.
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The Kirobo space robot is a diminutive mechanical person just 34 centimetres tall, built to converse with astronauts on long space voyages.
The robot, and its ground-based counterpart Mirata, are part of the Kibo Robot Project to develop new technologies to enhance human-robot interaction in space.
Kirobo speaks Japanese and is expected to talk to JAXA astronaut Koichi Wakata when he arrives at the space station in November.
The name of Kirobo is a merging of Kibo and robot, project officials have said.
Both robots come equipped with voice-recognition and face-recognition technology, as well as a camera, emotion recognition software and natural language processing.
"I want to help create a world where humans and robots can live together," Kirobo told reporters when the project was unveiled.