H-IIA (H2A) is an active expendable launch system operated by Mitsubishi Heavy Industries (MHI) for the Japan Aerospace Exploration Agency (JAXA). The liquid-fueled H-IIA rockets have been used to launch satellites into geostationary orbit, to launch a lunar orbiting spacecraft, and to launch an interplanetary space probe to Venus. Launches occur at the Tanegashima Space Center. Production and management of the H-IIA shifted from JAXA to MHI on April 1, 2007. Flight 13, which launched the lunar orbiter SELENE, was the first H-IIA launched after this privatization.

The H-IIA is a derivative of the earlier H-II rocket, substantially redesigned to improve reliability and minimize costs. There are four different variants of the H-IIA for various purposes.

The success rate of 95% of the H-2A is on a par with 96.4 percent for the Atlas V of the United States and 94.9 percent for the European Ariane 5.

The launch capability of an H-IIA launch vehicle can be enhanced by adding SRB-A (solid rocket booster or SRB) and Castor 4AXL (solid strap-on booster or SSB) to its basic configuration, creating a "family". The models are indicated by three or four numbers following the prefix "H2A". The first number in the sequence indicates the number of stages; the second the number of LRBs (Liquid rocket boosters); the third the number of SRBs; and, if present, the fourth number shows the number of SSBs. The first two figures are virtually fixed at "20", as H-IIA is always two-staged, and the plans for LRBs were cancelled and superseded by the H-IIB.