Multi-State System (MSS) is mathematical model of investigated object in reliability analysis. MSS allows present the investigated object in more detail than traditional Binary-State System. The importance analysis allows MSS reliability estimation depending on the system structure and its components states. Importance measures quantify the criticality of a particular component. They have been widely used as tools for identifying system weaknesses, and to priorities reliability improvement activities. New algorithms for calculation of the importance measures based on the methods of Multiple-Valued Logic are proposed. Direct Partial Logic Derivative and Multi-Valued Decision Diagram are used for these algorithms.