The article presents, in the matter of practical relationships between territorial self-government units and communal companies, theoretical grounds of the issue. Who are self-government bodies, who is representing them, and especially, what are their competences in case of founding and supervising communal companies. The author explains, how the autonomy of companies featuring the municipal property is developed, including considerations about the activity of their bodies (the assembly of the associates, the supervisory board, the executive) and their powers toward the self-government Executive (Mayor, president) and the Legislature of the municipality (Municipal Council)