A rocket carrying the Venus climate orbiter called "Akatsuki" blasted off from a Japanese space center in Kagoshima, southern Japan, the Japan Aerospace Exploration Agency said. Akatsuki means "dawn" in Japanese.
Akatsuki is expected to reach Venus' orbit in December. The orbiter will circle the planet for two years to examine its climate, including clouds, temperature and wind power, the agency said.
The development cost of Akatsuki was around 25 billion yen ($280 million).
The Venus mission follows Japan's first lunar probe, which completed a 19-month mission last year. The lunar project was to create a detailed map of the moon's surface and examine its mineral distribution.
Japan launched its first satellite in 1970 and has achieved several major scientific coups in space, including the launch of a probe that made a rendezvous with an asteroid.