PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can suppress overheating of an addition valve for adding an ammonia type reductant when the ammonia type reductant such as urea water cannot be added into an exhaust passage of the internal combustion engine because of freezing or the like.SOLUTION: When urea water is frozen (YES in S104), treatment (S108 to S114) for lowering the exhaust temperature in the exhaust passage as compared to the case (NO in S104, S120, S122) in which the urea water is not frozen is executed. In PM regeneration treatment using DPF catalyst, the treatment executes such temperature lowering treatment as to lower the regeneration temperature of the catalyst. According to the temperature lowering treatment, the temperature rising of exhaust accompanied by PM regeneration treatment can be suppressed and the overheating of a urea addition valve which cannot be cooled because of freezing of the urea water can be suppressed.