A control apparatus for an internal combustion engine having a variable valve actuation mechanism that is capable of arbitrarily setting opening and closing characteristics of an intake valve, comprising: for an environment condition (PA, TA) around the internal combustion engine including at least an atmospheric pressure, detecting means (54, 55) for detecting a present environment condition; storing means for storing a map indicating a relationship between an intake air amount and a lift amount of the intake valve in a standard environment condition (PA_STD, TA_STD); means for determining an intake air amount (GALTHCMD) requested by the internal combustion engine in a low load operation thereof; correcting means for correcting the requested intake air amount in the standard environment condition in such a manner as to indicate a requested intake air amount in the present environment condition; and means for referring to the stored map based on the corrected requested intake air amount (GALTHCMDF) to determine a target lift amount (ALCMD) corresponding to the corrected requested intake air amount, characterized in that a first operating region where an intake manifold pressure is changed according to an increase of a target intake air amount while keeping the lift amount constant, and a second operating region where the lift amount is changed according to an increase of the target intake air amount while keeping the intake manifold pressure constant at a predetermined reference gauge pressure are implemented, wherein, when the target intake air amount reaches the requested intake air amount under a predetermined reference phase, the first operating region is switched to the second operating region, wherein the map indicates a relationship between the intake air amount and the lift amount of the intake valve in the standard environment and the reference gauge pressure, wherein the target lift amount is applied to the first operating region. for an environment condition (PA, TA) around the internal combustion engine including at least an atmospheric pressure, detecting means (54, 55) for detecting a present environment condition; storing means for storing a map indicating a relationship between an intake air amount and a lift amount of the intake valve in a standard environment condition (PA_STD, TA_STD); means for determining an intake air amount (GALTHCMD) requested by the internal combustion engine in a low load operation thereof; correcting means for correcting the requested intake air amount in the standard environment condition in such a manner as to indicate a requested intake air amount in the present environment condition; and means for referring to the stored map based on the corrected requested intake air amount (GALTHCMDF) to determine a target lift amount (ALCMD) corresponding to the corrected requested intake air amount, characterized in that a first operating region where an intake manifold pressure is changed according to an increase of a target intake air amount while keeping the lift amount constant, and a second operating region where the lift amount is changed according to an increase of the target intake air amount while keeping the intake manifold pressure constant at a predetermined reference gauge pressure are implemented, wherein, when the target intake air amount reaches the requested intake air amount under a predetermined reference phase, the first operating region is switched to the second operating region, wherein the map indicates a relationship between the intake air amount and the lift amount of the intake valve in the standard environment and the reference gauge pressure, wherein the target lift amount is applied to the first operating region.