In March 1988 she ran her first marathon in Nagoya in 3:00:58 h In the following months, they continuously improved. Already two and a half years later she won the Tokyo International Women's Marathon, her sixth marathon start, third in 2:34:10 h 1990 she won the so-called Ōme Marathon over 30km and won the marathon in Tokyo in 2:31: 27 h and at the same time secured the Japanese title. 1992 finished the Nagoya Marathon, where they had four years earlier debuted in second place and was winner of the Gold Coast Marathon in Australia.
In the World Half Marathon Championships in 1993 in Brussels, she won the silver medal in both the individual and in the team competition. In the same year she was at the Tokyo International Women's Marathon runner-up. In 1994 she won the Paris Marathon in a personal Career of 2:27:55 h Later in the season she won at the World Half Marathon Championships in Oslo tenth place and won bronze in the team competition.
1996 Tanigawa took the Honolulu Marathon third place. In 1998, she won in a course record the Maui Marathon and finished sixth at the Hokkaido Marathon. For further starts the Honolulu Marathon in 1999 and 2000 she won the fourth and fifth. In the following years she had to pay tribute to their age and could not repeat her earlier results. At the Tokyo Marathon 2007, she came in second. However, there is no elite runners were then obliged. After this had changed, she won in 2009 in Tokyo, only the 67th place.
Mari Tanigawa is 1,60 m tall and has a competition weight of 44 kg. She lives in Tokyo's Arakawa district, where since 2000, named after her half-marathon will be held as a fun run. She appears regularly on talk shows on television in Japan and organizes seminars for runners. Her cousin is the hurdler Satoru Tanigawa.
- Half Marathon: 1:09:37 h, January 22, 1995, Tokyo
- Marathon: 2:27:55 h, April 24, 1994, Paris