CONTROLLER, CONTROLLING METHOD, AND RECORD MEDIUM

A controller according to an embodiment controls a hydrogen system including at least a hydrogen production system in which received power is planned in advance and a hydrogen production amount changes in accordance with the received power. The controller includes: a processor that calculates, in a preparation time period before a demand adjustment time period in which a target value of the received power is set in advance, a control command value such that input power to be inputted as the received power to the hydrogen production system matches the target value at a start of the demand adjustment time period; and a command controller that outputs the control command value calculated by the processor to the hydrogen production system.