A heat quantity control device has a heat flux sensor arranged between first and second heating elements arranged adjacently to each other, and a control section for controlling a heat quantity of the first and second heating elements. The heat flux sensor has an insulation board made of thermoplastic resin, first and second via holes formed in the insulation board penetrating in a thickness direction thereof. First and second layer connection members are embedded in the first and second via holes, respectively. The first and second layer connection members are made of different metals and alternately connected in series. The control section controls a heat quantity generated in the first and second heating elements based on the electromotive force generated in the heat flux sensors so that a heat flux flowing between the first and second heating elements becomes not more than a predetermined value.