A vehicle comprising: an internal combustion engine; an electrically-heated catalyst device provided in an exhaust passage of the internal combustion engine, the electrically-heated catalyst device including a conductive base material that generates heat upon being energized, and a catalyst heated through the conductive base material; and an electronic control unit configured to control base material electric power supply that is supplied to the conductive base material, the electronic control unit being configured to determine whether or not the conductive base material is in a stagnant period where temperature of the conductive base material partially stagnates in a prescribed temperature zone, the stagnant period occurring when water is present inside the electrically-heated catalyst device in a process of increase in temperature of the conductive base material; the electronic control unit being configured to calculate an internal water content that is a water content present inside the electrically-heated catalyst device; the electronic control unit being configured to determine that the conductive base material is in the stagnant period, when the internal water content is equal to or more than a prescribed water content, and the temperature of the conductive base material is equal to or more than a prescribed temperature that allows determination that the water present inside the electrically-heated catalyst device is evaporated, wherein the prescribed water content is a water content where a temperature difference, generated between a region where water is present and a region where water is not present in the conductive base material in a process of increase in temperature of the conductive base material when the electronic control unit controls the base material electric power supply to be the prescribed normal electric power supply, becomes equal to or more than a prescribed temperature difference, the prescribed normal electric power supply being supplied to the conductive base material when the electronic control unit determines that the conductive base material is not in the stagnant period; when determining that the conductive base material is in the stagnant period, the electronic control unit being configured to control the base material electric power supply to be lower than when determining that the conductive base material is not in the stagnant period based on the internal water content, wherein the base material electric power supply during the stagnant period is controlled, based on the internal water content, such that when the internal water content is large, the electronic control unit is configured to control the base material electric power supply to be lower than when the internal water content is small. an internal combustion engine; an electrically-heated catalyst device provided in an exhaust passage of the internal combustion engine, the electrically-heated catalyst device including a conductive base material that generates heat upon being energized, and a catalyst heated through the conductive base material; and an electronic control unit configured to control base material electric power supply that is supplied to the conductive base material, the electronic control unit being configured to determine whether or not the conductive base material is in a stagnant period where temperature of the conductive base material partially stagnates in a prescribed temperature zone, the stagnant period occurring when water is present inside the electrically-heated catalyst device in a process of increase in temperature of the conductive base material; the electronic control unit being configured to calculate an internal water content that is a water content present inside the electrically-heated catalyst device; the electronic control unit being configured to determine that the conductive base material is in the stagnant period, when the internal water content is equal to or more than a prescribed water content, and the temperature of the conductive base material is equal to or more than a prescribed temperature that allows determination that the water present inside the electrically-heated catalyst device is evaporated, wherein the prescribed water content is a water content where a temperature difference, generated between a region where water is present and a region where water is not present in the conductive base material in a process of increase in temperature of the conductive base material when the electronic control unit controls the base material electric power supply to be the prescribed normal electric power supply, becomes equal to or more than a prescribed temperature difference, the prescribed normal electric power supply being supplied to the conductive base material when the electronic control unit determines that the conductive base material is not in the stagnant period; when determining that the conductive base material is in the stagnant period, the electronic control unit being configured to control the base material electric power supply to be lower than when determining that the conductive base material is not in the stagnant period based on the internal water content, wherein the base material electric power supply during the stagnant period is controlled, based on the internal water content, such that when the internal water content is large, the electronic control unit is configured to control the base material electric power supply to be lower than when the internal water content is small.