A supply-demand control device that is mounted on a vehicle and that controls supply and demand of power or energy (Ws) in the vehicle, the supply-demand control device comprising a controller, the controller being configured to: set, for each of a plurality of priority ranks (P1 to P8) defined in advance as a priority order for supplying power or energy (Ws) in response to various possible demands from the vehicle for the power or the energy (Ws) based on predetermined categories classified in accordance with functions or performances required of the vehicle, an allowable limit indicating an upper limit of the power or the energy (Ws) that is allowed to be supplied in response to a demand of the each of the priority ranks (P1 to P8) while the power or the energy (Ws) that is supplied in response to a demand of the higher priority rank (P1 to P8) is secured, the allowable limit being set based on current values and control limit values determined by performing trimming within a range of a value set for a higher priority rank (P1 to P8) of each of the priority ranks (P1 to P8) with reference to an upper limit value and a lower limit value unique to each priority rank alone; detect the demand for the power or the energy (Ws), which occurs in the vehicle; and allocate, in order of the priority rank, the power or the energy (Ws) that is supplied from a predetermined supply source in response to the detected demand for the power or the energy (Ws), such that the supplied power or the supplied energy (Ws) is equal to or lower than the upper limit indicated by the allowable limit set for the each of the priority ranks (P1 to P8), characterized in that the controller further defines a plurality of occurrence frequency ranks each indicating a frequency of occurrence of the demand for the power or the energy (Ws), and the controller is configured to change the allowable limit for the each of the priority ranks (P1 to P8) in accordance with the occurrence frequency ranks. set, for each of a plurality of priority ranks (P1 to P8) defined in advance as a priority order for supplying power or energy (Ws) in response to various possible demands from the vehicle for the power or the energy (Ws) based on predetermined categories classified in accordance with functions or performances required of the vehicle, an allowable limit indicating an upper limit of the power or the energy (Ws) that is allowed to be supplied in response to a demand of the each of the priority ranks (P1 to P8) while the power or the energy (Ws) that is supplied in response to a demand of the higher priority rank (P1 to P8) is secured, the allowable limit being set based on current values and control limit values determined by performing trimming within a range of a value set for a higher priority rank (P1 to P8) of each of the priority ranks (P1 to P8) with reference to an upper limit value and a lower limit value unique to each priority rank alone; detect the demand for the power or the energy (Ws), which occurs in the vehicle; and allocate, in order of the priority rank, the power or the energy (Ws) that is supplied from a predetermined supply source in response to the detected demand for the power or the energy (Ws), such that the supplied power or the supplied energy (Ws) is equal to or lower than the upper limit indicated by the allowable limit set for the each of the priority ranks (P1 to P8), characterized in that the controller further defines a plurality of occurrence frequency ranks each indicating a frequency of occurrence of the demand for the power or the energy (Ws), and the controller is configured to change the allowable limit for the each of the priority ranks (P1 to P8) in accordance with the occurrence frequency ranks.