Apparatus for casting a composite metal ingot, which comprises: a direct chill casting apparatus having a casting mold with at least two chambers for casting a composite ingot having at least two metal layers; and troughs (25, 26) configured for supplying streams of molten metal to said at least two casting chambers; characterized in that the apparatus further comprises: at least two temperature sensors (40, 41) configured for monitoring inlet temperatures of at least two of said streams of molten metal at positions adjacent to inlets (20A, 28) of the casting chambers fed with said at least two streams; a device configured for comparing said monitored temperatures from said at least two temperature sensors (40, 41) with predetermined set temperatures for said at least two streams to detect temperature differences from said set temperatures for each of said at least two streams; and a controller configured for adjusting ingot casting speed as a casting variable that affects molten metal temperatures entering or within the casting chambers and affects all of the metal layers of the composite ingot based on a summation or average of said temperature differences detected for said at least two streams, so as to minimize adverse casting effects caused by said one or more temperature differences. a direct chill casting apparatus having a casting mold with at least two chambers for casting a composite ingot having at least two metal layers; and troughs (25, 26) configured for supplying streams of molten metal to said at least two casting chambers; characterized in that the apparatus further comprises: at least two temperature sensors (40, 41) configured for monitoring inlet temperatures of at least two of said streams of molten metal at positions adjacent to inlets (20A, 28) of the casting chambers fed with said at least two streams; a device configured for comparing said monitored temperatures from said at least two temperature sensors (40, 41) with predetermined set temperatures for said at least two streams to detect temperature differences from said set temperatures for each of said at least two streams; and a controller configured for adjusting ingot casting speed as a casting variable that affects molten metal temperatures entering or within the casting chambers and affects all of the metal layers of the composite ingot based on a summation or average of said temperature differences detected for said at least two streams, so as to minimize adverse casting effects caused by said one or more temperature differences. at least two temperature sensors (40, 41) configured for monitoring inlet temperatures of at least two of said streams of molten metal at positions adjacent to inlets (20A, 28) of the casting chambers fed with said at least two streams; a device configured for comparing said monitored temperatures from said at least two temperature sensors (40, 41) with predetermined set temperatures for said at least two streams to detect temperature differences from said set temperatures for each of said at least two streams; and a controller configured for adjusting ingot casting speed as a casting variable that affects molten metal temperatures entering or within the casting chambers and affects all of the metal layers of the composite ingot based on a summation or average of said temperature differences detected for said at least two streams, so as to minimize adverse casting effects caused by said one or more temperature differences.