Acquiring information that has an impact on a country's security, i.e. its independence, sovereignty and international position, by unauthorized persons, whether from another country's intelligence services or criminal groups, may have far-reaching consequences. Therefore, to preserve the stability of the state and give a sense of security to its citizens, the most important task and duty of the government is to protect them. This can be provided by an efficiently functioning system that will guarantee restrictions on access to classified information, its proper processing, as well as the use of appropriate and suffcient physical and ICT security measures. For this reason, this system requires at the state level precisely defined rules and norms based on the law, defining the principles of creating classified information, how to protect it and sanctions that can be applied in the event of non-compliance. The protection of information having a significant impact on the functioning of the Polish state in each period of its existence was an important element of defense and security policy. After regaining independence, the protection of state secrets took on special significance both for the country's existence and the foundations of its existence. It was realized that their disclosure could be fatal to its organization and functioning, as well as defense capabilities. The presented material presents the evolution of the protection of classified information in Poland, and its importance for the security and defense of the state by ensuring the effectiveness(concealing) of actions aimed at their implementation.