Using a large panel data set that samples over 4000 Japanese, we analyze changes in people’s subjective well-being (happiness) and altruistic worldview before and after the Great East Japan Earthquake. As a result we find that 1) more people replied that their happiness improved after the earthquake than said it worsened, and also that 2) many more Japanese people became more altruistic since the earthquake, even in the most affected areas. One possible interpretation of these results is that an increase in altruism due to the earthquake spurred people to give to charity, which in turn increased their happiness. Our regression analysis yields results that are consistent with this story.