A startup control apparatus for an internal combustion engine, which is applied to a spark ignition type internal combustion engine in which automatic stoppage and automatic startup are executed according to a predetermined condition, and which executes a fuel cut when a rotational speed of the internal combustion engine exceeds a reference rotational speed that is higher than a target idle rotational speed (Ni) at the beginning of the automatic startup, the startup control apparatus comprising: variable control means for executing ignition timing variable control during startup of the internal combustion engine such that an ignition timing of the internal combustion engine is retarded under a first condition and advanced under a second condition, prohibiting means for setting respective conditions for prohibiting the ignition timing variable control executed by the variable control means during the manual startup of the internal combustion engine and during the automatic startup of the internal combustion engine individually, wherein the first condition indicates an increase in the rotational speed of the internal combustion engine during startup of the internal combustion engine; and the second condition indicates a decrease in the rotational speed of the internal combustion engine during startup of the internal combustion engine, or wherein the first condition indicates the rotational speed of the internal combustion engine being higher than the target idle rotational speed (Ni) during startup of the internal combustion engine; and the second condition indicates the rotational speed of the internal combustion engine being lower than the target idle rotational speed (Ni) during startup of the internal combustion engine, wherein further the prohibiting means sets a predetermined time from beginning of the startup during which the ignition timing variable control is prohibited to be longer during the automatic startup of the internal combustion engine than during the manual startup. variable control means for executing ignition timing variable control during startup of the internal combustion engine such that an ignition timing of the internal combustion engine is retarded under a first condition and advanced under a second condition, prohibiting means for setting respective conditions for prohibiting the ignition timing variable control executed by the variable control means during the manual startup of the internal combustion engine and during the automatic startup of the internal combustion engine individually, wherein the first condition indicates an increase in the rotational speed of the internal combustion engine during startup of the internal combustion engine; and the second condition indicates a decrease in the rotational speed of the internal combustion engine during startup of the internal combustion engine, or wherein the first condition indicates the rotational speed of the internal combustion engine being higher than the target idle rotational speed (Ni) during startup of the internal combustion engine; and the second condition indicates the rotational speed of the internal combustion engine being lower than the target idle rotational speed (Ni) during startup of the internal combustion engine, wherein further the prohibiting means sets a predetermined time from beginning of the startup during which the ignition timing variable control is prohibited to be longer during the automatic startup of the internal combustion engine than during the manual startup.