An internal combustion engine comprising: a reducing agent feed valve arranged in an engine exhaust passage; and a reducing agent injection control device for controlling an action of injection of a reducing agent from the reducing agent feed valve, wherein the reducing agent feed valve is provided with a nozzle hole which opens inside of the engine exhaust passage and is comprised of a type of feed valve which is controlled to open and close at an inside end side of the nozzle hole, wherein the reducing agent injection control device is configured to perform an injection control for exhaust treatment such that the reducing agent is injected in an amount, which is necessary for exhaust treatment, wherein the reducing agent injection control device is configured to perform an injection control for preventing clogging such that the reducing agent is injected from the reducing agent feed valve in a smaller amount than the amount, which is necessary for exhaust treatment, to prevent the nozzle hole of the reducing agent feed valve from clogging, wherein the reducing agent injection control device is configured such that the reducing agent for preventing clogging from the reducing agent feed valve is injected during a period of suspension of the injection control for exhaust treatment, when a feed of fuel to a combustion chamber is stopped, and wherein the reducing agent injection control device is configured such that an injection of the reducing agent for preventing clogging from the reducing agent feed valve is stopped after once injecting the reducing agent for preventing clogging from the reducing agent feed valve during a period of suspension of the injection control for exhaust treatment, when a feed of fuel to a combustion chamber is stopped, until the reducing agent injection control for exhaust treatment is resumed. a reducing agent feed valve arranged in an engine exhaust passage; and a reducing agent injection control device for controlling an action of injection of a reducing agent from the reducing agent feed valve, wherein the reducing agent feed valve is provided with a nozzle hole which opens inside of the engine exhaust passage and is comprised of a type of feed valve which is controlled to open and close at an inside end side of the nozzle hole, wherein the reducing agent injection control device is configured to perform an injection control for exhaust treatment such that the reducing agent is injected in an amount, which is necessary for exhaust treatment, wherein the reducing agent injection control device is configured to perform an injection control for preventing clogging such that the reducing agent is injected from the reducing agent feed valve in a smaller amount than the amount, which is necessary for exhaust treatment, to prevent the nozzle hole of the reducing agent feed valve from clogging, wherein the reducing agent injection control device is configured such that the reducing agent for preventing clogging from the reducing agent feed valve is injected during a period of suspension of the injection control for exhaust treatment, when a feed of fuel to a combustion chamber is stopped, and wherein the reducing agent injection control device is configured such that an injection of the reducing agent for preventing clogging from the reducing agent feed valve is stopped after once injecting the reducing agent for preventing clogging from the reducing agent feed valve during a period of suspension of the injection control for exhaust treatment, when a feed of fuel to a combustion chamber is stopped, until the reducing agent injection control for exhaust treatment is resumed. wherein the reducing agent feed valve is provided with a nozzle hole which opens inside of the engine exhaust passage and is comprised of a type of feed valve which is controlled to open and close at an inside end side of the nozzle hole, wherein the reducing agent injection control device is configured to perform an injection control for exhaust treatment such that the reducing agent is injected in an amount, which is necessary for exhaust treatment, wherein the reducing agent injection control device is configured to perform an injection control for preventing clogging such that the reducing agent is injected from the reducing agent feed valve in a smaller amount than the amount, which is necessary for exhaust treatment, to prevent the nozzle hole of the reducing agent feed valve from clogging, wherein the reducing agent injection control device is configured such that the reducing agent for preventing clogging from the reducing agent feed valve is injected during a period of suspension of the injection control for exhaust treatment, when a feed of fuel to a combustion chamber is stopped, and wherein the reducing agent injection control device is configured such that an injection of the reducing agent for preventing clogging from the reducing agent feed valve is stopped after once injecting the reducing agent for preventing clogging from the reducing agent feed valve during a period of suspension of the injection control for exhaust treatment, when a feed of fuel to a combustion chamber is stopped, until the reducing agent injection control for exhaust treatment is resumed.