A control device for a multi-phase converter including converter circuits of m phases of which each includes a switching element includes: a driven phase number control unit configured to control the multi-phase converter in n-phase driving or m-phase driving; a storage unit configured to store first and second patterns; a selection unit configured to select the first or second pattern while the multi-phase converter is stopped, an on/off control unit configured to perform on/off control on the switching elements of the number of driven phases; and a prediction unit configured to predict a predicted correlation value which is correlated with a time ratio which is a ratio of a time in which control in the m-phase driving is predicted to be performed to a time in which control in the n-phase driving is predicted to be performed in a predetermined time.