An electric power generation controller for use in an aircraft is a controller of an electric power generating system configured such that: a manual transmission changes speed of rotational power of an aircraft engine; a continuously variable transmission changes the speed of the rotational power which has been changed in speed by the manual transmission; and the continuously variable transmission transmits the rotational power to an electric power generator. The electric power generation controller includes: a manual transmission control section configured to, when a predetermined shift condition is satisfied, control the manual transmission to switch a gear stage of the manual transmission; and a continuously variable transmission control section configured to, when the shift condition is satisfied, control the continuously variable transmission to such a side that fluctuation of an output rotational frequency of the manual transmission by the switching of the gear stage of the manual transmission is canceled.