A catalyst substrate may include a ceramic base body including first and second ends, the second end being opposite to the first end, and the ceramic base body being provided with a plurality of cells each extending between the first and second ends; and a plurality of metal particles or metal fragments introduced into one or more internal spaces of one or more selected cells in the plurality of cells. Each of the plurality of metal particles or metal fragments has a size equal to or less than an opening width of the cell. The plurality of metal particles or metal fragments is configured to generate heat in accordance with varying magnetic field.