An object is to provide a technology with which the temperature of exhaust gas can be raised with improved efficiency in cases where a catalyst apparatus including a catalyst having an oxidizing ability is provided in an exhaust passage of an internal combustion engine. According to the present invention, a catalyst apparatus 6 that is provided in the exhaust passage 1 of the internal combustion engine and to which reducing agent is supplied from upstream when the temperature of the exhaust gas is to be raised is equipped with at least first and second catalysts 4, 5 having an oxidizing ability. The first catalyst 4 is configured in such a way that the exhaust gas flows through a gap between its outer circumferential surface and the inner circumferential surface of the exhaust passage. The second catalyst 5 is disposed downstream of the first catalyst 4 with a space 10 having a specific width Ws between it and the first catalyst 4.