This paper presents the EXM-algorithm, which locates multiple logic design errors in a combinational circuit with multiple output. The error possibility index and the six-valued simulation method have been enhanced to be applied to multiple output circuit. The algorithm locates multiple errors even if they belong to different cone circuits, and processes faster than the conventional EX-algorithm for circuits with the similar gate sizes. Experimental results have shown that the algorithm locates all errors at high hit ratio for ISCAS benchmark circuits and some other circuits.