The android took off from the island of Tanegashima in an unmanned rocket also carrying supplies for crew onboard the International Space Station (ISS).
Measuring 34cm (13 inches), Kirobo is due to arrive at the ISS on 9 August.
It is part of a study to see how machines can lend emotional support to people isolated over long periods.
The launch of the H-2B rocket was broadcast online by the Japan Aerospace Exploration Agency (Jaxa).
The unmanned rocket is also carrying drinking water, food, clothing and work supplies to the six permanent crew members based at the ISS.
Kirobo’s name derives from the Japanese words for “hope” and “robot”.
The small android weighs about 1kg (2.2 pounds) and has a wide range of physical motion. Its design was inspired by the legendary animation character Astro Boy.
Kirobo has been programmed to communicate in Japanese and keep records of its conversations with Mr Wakata who will take over as commander of the ISS later this year.
In addition, it is expected to relay messages from the control room to the astronaut.
“Kirobo will remember Mr Wakata’s face so it can recognise him when they reunite up in space,” the robot’s developer, Tomotaka Takahashi said.
“I wish for this robot to function as a mediator between a person and machine, or a person and the Internet, and sometimes even between people.”
The biggest challenge was to make the android compatible with space, Mr Takahashi added.
Dozens of tests were carried out over nine months to ensure Kirobo’s reliability.
Kirobo has a twin robot on Earth called Mirata, which will monitor any problems its electronic counterpart may experience in space.
“It’s one small step for me, a giant leap for robots,” Mirata said of the mission last month.
The endeavour is a joint project between Mr Takahashi, car producer Toyota and advertising company Dentsu.
Source : http://www.bbc.co.uk/news/world-asia-23565121