A multipole in electric circuit theory (unlike to electric or magnetic field multipole calculation methods) is a circuit or a part of a circuit, which is connected to other circuits by a definite number of terminals (poles). An expression is given for determining the number of parameters of the equivalent diagramof a multipole depending on the number of poles. Unlike the generally known four-pole theory that can be used only if both incoming currents of the four-pole (and the same for both outgoing currents) are mutually equal, a so called generalized four-pole is considered, which does not comply with the so-called rule of regularity. In general case, the equivalent diagram of such a generalized, passive four-pole (that conforms to the reciprocity principle) should contain six passive elements unlike the “usual” regular four-pole, equivalent diagram of which needs only three resistances. Mathematical analogy of an electric circuit multipole and a charged system of bodies is shown. An expression is given for determining the number of parameters of the equivalent diagram depending on the number of poles. A double T-type diagram of a generalized four-pole is considered. Equivalent diagrams of an active multipole have been created by replacing the inner sources with outer sources of current or voltage