A catalyst device includes a catalyst, a heating element 31 and a case 20. The case includes a end portion 22 protruding on an upstream side in the gas discharging direction and which is an insulating portion that insulates electricity. The heating element 31 includes an end on an upstream side in the gas discharging direction. The catalyst device further includes an outer tube 50 that is separated from the end portion of the case in a radial direction to cover the end portion and is formed by a turbine housing 110 that houses a turbine wheel 130 of the forced-induction device (turbo charger).