On June 8, 1997, when Miyamoto was 18 years old, she debuted and scored a goal for the Japan national team against China. She was a member of Japan for 1999, 2003, 2007 World Cup and 2004 Summer Olympics. She also played at 1997, 1999, 2003 AFC Championship, 1998 and 2002 Asian Games. She played 77 games and scored 13 goals for Japan until 2007.