The heater includes a heater main body, a housing storing the heater main body therein, and a coating material arranged in at least a part between the heater main body and the housing and covering at least a part of the heater main body. The coating material is a material containing at least one of ceramic and glass, the heater main body has a cylindrical honeycomb structural portion having partition walls separating and forming a plurality of cells and a pair of electrode portions disposed on a side face of the honeycomb structural portion, the housing contains the heater main body so as to cover the side face side of the heater main body, and the partition walls of the honeycomb structural portion is of a material containing ceramic as the main component and produces heat by energization.