A method and apparatus for allocating channel bandwidths in a wireless IPTV system is provided. The method includes measuring, if an additional service offering request is received in a saturation channel state, remaining execution times until a service of each terminal that is currently receiving a service is terminated, and setting a minimum of the measured remaining execution times to a unit time; calculating a securable channel bandwidth per the unit time with respect to each terminal that is currently receiving a service; and allocating, if the summation of the securable channel bandwidths per the unit time is equal to or greater than a channel bandwidth required to provide the additional service, the requested channel bandwidth in order to provide the additional service.