Abstract <p> Quantum filtering equations for mixed states were developed in the eighties of the last century. Since then, the problem of constructing a rigorous mathematical theory for these equations in the basic infinite-dimensional settings has been a challenging open mathematical problem. In a previous paper, the author developed the theory of these equations in the case of bounded coupling operators, including a new version that arises as the law of large numbers for interacting particles under continuous observation and thus leading to the theory of quantum mean field games. In this paper, the main body of these results is extended to the basic cases of unbounded coupling operators. </p> <p> <b> DOI</b> 10.1134/S1061920825600825 </p>