While attending Doshisha University, Masaharu Taguchi attracted attention for the first time, winning the 100 metre freestyle event for newcomers at the Meiji Jingu Games in 1933. After moving to Rikkyo University he won the national title in the 100 metre freestyle which earned him a place on the Japanese team for the 1936 Berlin Olympics. There he placed fourth in the final of the 100 freestyle behind Hungarian Ferenc Csik and his teammates Masanori Yusa and Shigeo Arai, although he was considered by many as the true silver medalist. Taguchi did win a gold medal as a member of the Japanese 4x200 free relay. In the same year, he clinched the Japanese championship in the 200 free.
After graduating, Taguchi worked for the Daimaru Department Store and at the company’s swimming club coaching, among others, future gold medalist Masaru Furukawa. In 1961 he joined the development team of the Japan Swimming Federation and acted as head coach of the Japanese swimming team at the 1964 Tokyo Olympics.