A control apparatus for an internal combustion engine comprising: a fuel supply section which supplies a fuel to said internal combustion engine; a urea-SCR catalyst, which is disposed in an exhaust passage of said engine, and which purifies nitrogen oxides contained in an exhaust gas discharged from said engine by reducing said nitrogen oxides with ammonia produced from urea-water supplied to said urea-SCR catalyst; a urea-water supply section which supplies said urea-water to said urea-SCR catalyst; a low pressure gas recirculating section including a low pressure EGR pipe and a low pressure EGR valve disposed in said low pressure EGR pipe, wherein said low pressure EGR pipe forms a low pressure EGR passage communicating between a position downstream of said urea-SCR catalyst in said exhaust passage and an intake passage of said engine, and an opening degree of said low pressure EGR valve is varied so as to vary a passage cross sectional area of said low pressure EGR passage; and a control section, which controls an amount of said fuel supplied to said engine from said fuel supply section based on a parameter indicative of an operating state of said engine, controls said opening degree of said low pressure EGR valve based on said parameter indicative of said operating state of said engine, and performs a urea-water for reducing nitrogen oxides supply control to control an amount of said urea-water supplied from said urea-water supply section based on said parameter indicative of said operating state of said engine in such a manner that ammonia of an amount estimated to be required to reduce nitrogen oxides contained in said exhaust gas is produced in said urea-SCR catalyst, wherein, said control section is configured to: estimate, based on said parameter indicative of said operating state of said engine, an amount of an acid condensed water which is produced from a gas passing through said low pressure EGR passage and is accumulated in said low pressure EGR passage and said intake passage; determine whether or not a specific condition is satisfied, said specific condition including a condition that said estimated amount of said acid condensed water is equal to or larger than an acid condensed water amount threshold; and perform, when said specific condition is satisfied, a urea-water for producing ammonia supply control for a predetermined time to set an amount of said urea-water to be supplied from said urea-water supply section to an amount larger than an amount required for said urea-water for reducing nitrogen oxides supply control so that ammonia flows out from said urea-SCR catalyst while a gas flowing out from said urea-SCR catalyst is passing through said low pressure EGR passage and flowing into said intake passage. a fuel supply section which supplies a fuel to said internal combustion engine; a urea-SCR catalyst, which is disposed in an exhaust passage of said engine, and which purifies nitrogen oxides contained in an exhaust gas discharged from said engine by reducing said nitrogen oxides with ammonia produced from urea-water supplied to said urea-SCR catalyst; a urea-water supply section which supplies said urea-water to said urea-SCR catalyst; a low pressure gas recirculating section including a low pressure EGR pipe and a low pressure EGR valve disposed in said low pressure EGR pipe, wherein said low pressure EGR pipe forms a low pressure EGR passage communicating between a position downstream of said urea-SCR catalyst in said exhaust passage and an intake passage of said engine, and an opening degree of said low pressure EGR valve is varied so as to vary a passage cross sectional area of said low pressure EGR passage; and a control section, which controls an amount of said fuel supplied to said engine from said fuel supply section based on a parameter indicative of an operating state of said engine, controls said opening degree of said low pressure EGR valve based on said parameter indicative of said operating state of said engine, and performs a urea-water for reducing nitrogen oxides supply control to control an amount of said urea-water supplied from said urea-water supply section based on said parameter indicative of said operating state of said engine in such a manner that ammonia of an amount estimated to be required to reduce nitrogen oxides contained in said exhaust gas is produced in said urea-SCR catalyst, estimate, based on said parameter indicative of said operating state of said engine, an amount of an acid condensed water which is produced from a gas passing through said low pressure EGR passage and is accumulated in said low pressure EGR passage and said intake passage; determine whether or not a specific condition is satisfied, said specific condition including a condition that said estimated amount of said acid condensed water is equal to or larger than an acid condensed water amount threshold; and perform, when said specific condition is satisfied, a urea-water for producing ammonia supply control for a predetermined time to set an amount of said urea-water to be supplied from said urea-water supply section to an amount larger than an amount required for said urea-water for reducing nitrogen oxides supply control so that ammonia flows out from said urea-SCR catalyst while a gas flowing out from said urea-SCR catalyst is passing through said low pressure EGR passage and flowing into said intake passage.