Electronic structures and magnetic properties of dilute aluminium pnictides (Al1-xTx)M are calculated on the basis of density functional theory, where T denotes 3d transition metal (TM) elements and M denotes As and P elements. Among the TM elements, V, Cr, Fe and Co are used as dopants, which are used sequentially at the cation sites of the pnictide semiconductors. Ferromagnetic (FM) critical temperature (TC) is calculated using the mean-field approximation combined with the Korringa-Kohn-Rostoker Green’s function method. Self-consistent energy minimisation scheme is used to select the stable magnetic state as well as the calculation of TC between the FM state and disordered local moment (DLM) state. Furthermore, electronic structures are calculated for the stable magnetic states of these compounds. A significant change in TC is obtained for varying doping concentrations. Saturated magnetisations of those stable compounds are consistent with the variation of doping concentrations, whereas spin magnetisations are found to be nearly independent of doping concentrations.