The Joint International Conference of the 7th Supercomputing in Nuclear Application and the 3rd Monte Carlo (SNA + MC2010) will be held in Tokyo, Japan, from Oct. 17 to Oct. 21, 2010. SNA is a series of conferences which started after the first conference at Mito Japan in 1990 and follows conferences held in Karlsruhe Germany (1993), Saratoga Springs USA(1997), Tokyo Japan(2000), Paris France(2003) and Monterey USA(2007). Periodic MC can be traced backed to the conference in Lisbon Portugal(2000), subsequently, Chattanooga USA(2005). The conference is designed to discuss computational science, technology and applications concerning nuclear research and Monte Carlo simulation from wide viewpoints. The conference is mainly composed of plenary and technical sessions. Submitted papers will be presented in oral or poster sessions scheduled from October 18 to 21. It is planned that papers of high quality will be peer reviewed and published in special issues of Journal of Nuclear Science and Technology. Student award will be given to young students presenting outstanding works.