A flash type AD converter includes a group of comparators divided into blocks each including 2.sup.N comparators (N=1, 2, ---), each comparing an input signal with one of a plurality of reference signals, each having individually different voltage levels. One of the comparators may correspond to a level change point where the voltage level of the input signal is higher than that of the reference signal of that comparator which then generates a specific output different from those of the remaining comparators. The converter generates a binary-coded output on the basis of the specific output generated from the level change point comparator. When any one of the plural comparators belonging to one of the blocks generates the specific output, the specific output is applied as an inhibit signal to inhibit appearance of an output from a block including comparators having reference voltage signals with corresponding levels lower than those of the comparators of the block to which the comparator generating the specific output belongs.