In 1993, a mutation in the superoxyde dismutase gene, SOD1, was found causative for familial ALS, suggesting that free radical-related injury may be involved in ALS pathogenesis. Therefore, clinical trials were conducted with ALS patients using a free radical scavenger, edaravone, which was already approved for acute phase treatment of cerebral infarction in Japan. Because edaravone showed a therapeutic effect in suppressing the progression of ALS symptoms, it was approved as a new therapeutic agent in Japan, in June, 2015. In this article, we discuss the recent progress of basic and clinical research for the development of new ALS treatments.