In recent years, teachers' increased workloads have become an issue for policy, and have been multiply pointed out, deriving as they do from peripheral duties such as paperwork, in academic research as well. However, these mentions have not been based on sufficiently solid proof. Here, this paper compares teacher working hours surveys extant from the 1950s-1960s and from the late 2000s, using a general linear model. Results show that it is not necessarily the case that teachers in the late 2000s are spending more time on peripheral duties like paperwork than their 1950s-1960s counterparts, but that the time they spend on educational activities (in particular, extracurricular activities) is longer. [This article was translated by Nadezhda Murray. It was originally published, in Japanese, in "The Japanese Journal of Educational Research" Vol. 82, No.1, 2015.]