In this paper, the legal regulation of construction contract with different and often mutually contradictory legal acts will be elaborated. A construction contract is one of the most complicated legal obligation due to a number of circumstances related to the implementation of the contract, which can change suddenly. Furthermore, the fact of the large number of potential participants speaks of the complexity of the contract itself. These are primarily the project sponsor and the contractor, followed by design-builders, supervising engineers, and project managers. Changes in the prices of the elements on the basis of which the price of the works is determined appear regularly in very short periods. Prices change very strongly, sometimes at the level of just a few months. Because of this, in practice, the need to contract certain protective mechanisms has arisen. Most often, a sliding scale or an index clause is explicitly contracted