Research Note by Soichiro Takagi: “Open data generally refers to a movement in which public organizations provide data in a machine-readable format to the public, so that anyone can reuse the data. Open data is becoming an important phenomenon in Japan. At this moment, utilization of open data in Japan is emerging with collaborative efforts among small units of production such as individuals. These collaborations have been also observed in the Open Source Software (OSS) movement, but collaboration in open data is somewhat different in respect to small-scale, distributed collaboration. The aim of this research note is to share the phenomena of open data as an object of economic analysis with readers by describing the movement and providing a preliminary analysis. This note discusses how open data is associated with mass collaboration from the viewpoint of organizational economics. It also provides the results of empirical analysis on how the regional characteristics of municipalities affect the decision of local governments to conduct open data initiatives.”