The combination of t-Bu-P-4 and alcohol was found to be an excellent catalytic system for the controlled/living ring-opening polymerization (ROP) of N,N-disubstituted glycidylamine derivatives, such as N,N-dibenzylglycidylamine (DBGA), N-benzyl-N-methylglycidylamine, N-glycidylmorpholine, and N,N-bis(2-methoxyethyl)glycidylamine, to give well-defined polyethers having various pendant tertiary amino groups with predictable molecular weights and narrow molecular weight distributions (typically M-w/M-n, < 1.2). The tBu-P-4-catalyzed ROP of these monomers in toluene at room temperature proceeded in a living manner, which was confirmed by a MALDI-TOF MS analysis, kinetic measurement, and postpolymerization experiment. The well-controlled nature of the present system enabled the production of the block copolymers composed of the glycidylamine monomers. The polyethers having pendant primary and secondary amino groups, i.e., poly(glycidylamine) and poly(glycidylmethylamine), respectively, were readily obtained by the debenzylation of poly(DBGA) and poly(BMGA), respectively, through the treatment with Pd/C in THF/MeOH under a hydrogen atmosphere. To the best of our knowledge, this report is the first example of the controlled/living polymerization of glycidylamine derivatives, providing a rapid and comprehensive access to the polyethers having primary, secondary, and tertiary amino groups.