The starting point of this analysis is a statement that the authors of Poland's Constitution have decided not to include therein a precise basis for the conduct of economic activity by the State. According to Article 1 of the Constitution which establishes the principle of a common good, the State - as a structure of power - is obligated to pursue the public interest in each area of its activity. Economic activity of the State should contribute to the achievement of common good. The task of identification of the common good is conferred, principally, on the executive and legislative branches of government which are empowered to take decisions (within widely defined constitutional limits) concerning the conduct of economic activity by the State and about the use of profits resulting therefrom. There is no obstacle to the State conducting profitable economic activity, provided that profits are used for the benefit of public interest. Referring to Article 2 of the Constitution, which establishes the principle of social justice, it is the duty of the State to correct market mechanisms which may result in discrimination against some individuals or social groups. Involvement by the State in economic activity may be one the means of intervention. The commitment to the principle of social justice may be perceived as the basis of operation of an entrepreneur. A social market economy, based, among other things, on the freedom of economic activity, is the basis of the economic system of the Republic of Poland (Article 20 of the Constitution). Stressing the significance of private ownership for shaping the economic system, qualifies public economic activity as merely an exception. Any form of economic activity by the State is permissible if it conforms with the principle of the common good. The exceptional nature of public economic activity also ensues from the norm which establishes the principle o subsidiarity. According to this principle, the State should intervene in the area of social and economic relations only when individuals are not able to address the challenges by themselves. The principle of subsidiary can sometimes impose on the State an obligation to intervene and engage in economic activity in the event that private subjects are not (for objective reasons) able to operate without State intervention. Public economic activity takes different forms, all of which are characterised by the term: public entrepreneur, which is defined in this article.