The aim of the present study was to investigate the laryngeal adjustments for voiced versus voiceless distinction in Japanese consonant production by means of laryngeal electromyography (EMG) and fiberoptic observation. Multichannel EMG recordings were taken of a Japanese subject and the data were computer-processed to obtain the averaged activity patterns of the five intrinsic laryngeal muscles with special reference to the voicing distinction in consonant production in various phonetic environments. It was found that there were apparent reciprocal patterns in the posterior cricoarytenoid (PCA) and the interarytenoid (INT) in terms of significant negative correlation, and active control of PCA for voicelessness was demonstrated. The patterns of the thyroarytenoid and the lateral cricoarytenoid were different from that of INT even though these two muscles are usually classified as the members of the adductor group, and their activity levels were apparently influenced by the phonetic environment. A possible contribution of the cricothyroid (CT) to the voicing distinction was also pointed out but further investigations on acoustic parameters seem to be mandatory in more critical interpretation of CT activity in speech.