Even when a first differentiation value is equal to or greater than a first threshold value, this optical disc device does not confirm “CD” to be the differentiation result, as long as a first focus error signal FE1 or a first focus sum signal FS1 is less than a second threshold value; and even when the first differentiation value is equal to or greater than a second differentiation value, this optical disc device does not confirm “CD” to be the differentiation result, as long as the signal FE1 is less than a second focus error signal FE2, or as long as the signal FS1 is less than a second focus sum signal FS2. The signals FE1 and FS1 are obtained when a CD laser beam is directed onto an optical disc. The signals FE2 and FS2 are obtained when a DVD laser beam is directed onto the disc.