All master's theses that are written in public educational establishments and lead to a degree are, according to the Act on the Openness of Government Activities, official documents that are public unless specifically otherwise provided. (The Constitution of Finland, Section 12.2; Act on the Openness of Government Activities, Section 1).
The Act also defines what kind of official documents are secret. Such are for example documents that contain information on business or professional secrets and documents that contain the basic materials for a dissertation or other scientific study, or the assessment of the same (Section 24). In master's theses the secret information should only be included in the background material.
According to the guidelines published by the MInistry of Education and Culture (2/500/2004) universities and universities of applied sciences must ensure that master's theses do not contain secret material, and that they are available to the public immediately after their approval.