The principle of one-to-one correspondence between motive and activity (an activity can have but one underlying motivation) is argued. It follows from the principle that the phenomenon of polymotivation means that there develop simultaneously several activities. Each of them, in its turn, may be provoked by a number of needs which combine in a number of ways. Within a single activity all these components are united by the motive defined as a subjective value of this particular activity. The value represents meaningful attitude of the person to his needs and to the situation of their realization.