A Martian rover mission is currently entertained in Japan Aerospace Exploration Agency (JAXA) for launch in 2020s. The primary scopes of this mission are to demonstrate the entry-descent-landing and surface exploration technologies on Mars, to search for signs of live organisms, and to determine when the ocean is lost in the past Martian history. In order to cut down the mission cost and the development risk, the spacecraft is designed as a compact medium-class spacecraft whose total wet mass at Earth departure is approximately 900 kg. The spacecraft system consists of the cruise module and the atmospheric entry module which is subdivided into a forebody and an aftbody aeroshell, a landing module, and a rover, in a typical reference mission design under consideration. The current status of research and development is briefly presented as well.