An aspect of the present invention relates to a control device for an exhaust gas post-treatment device that includes a filter that collects a particulate substance in exhaust gas of an engine and an oxidation catalyst provided upstream of the filter, and that is configured to regenerate the filter by an action of the oxidation catalyst, the control device including a notification unit configured to, in a case in which forced regeneration for forcibly increasing a temperature of the exhaust gas is carried out, when the number of times it is estimated that the temperature of the exhaust gas is lower than a light-off temperature for a period of time equal to or longer than a prescribed period of time exceeds a prescribed threshold, issue a notification indicating that there is a problem in an operation state of the engine.