Shigeo Arai (新井 茂雄, Arai Shigeo, August 8, 1916 – July 19, 1944) was a Japanese freestyle swimmer who competed at the 1936 Olympics. He won a gold medal in 4 × 200 m freestyle relay, setting a world record. In the individual 100 m race he finished almost simultaneously with Masanori Yusa and Masaharu Taguchi and was awarded a bronze medal. Those Games were the only international competition for Arai, though he won three national titles in the 100 m and four in the 200 m freestyle between 1937 and 1940.