This essay analyzes the concept of common good in "The Prince" and "The Discourses". According to Machiavelli the common good cannot be founded upon any sort of firm ground: neither metaphysical nor divine, not even natural. It originates from the necessary simultaneity of conflicting elements: historical-political disputes or ethical dycothomies. Task of the politician, who, according to Machiavelli, radically distinguishes himself for the tyrant, is to provoke a constructive tension among these elements, in order to pursue the common good. The latter consists in the protection of life, family, property and, in a republican context, in the participation to the public freedom.