Voice and speech disorders are one of the most important issues after subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease patients; however, their characteristics remain unclear. We performed a comprehensive voice evaluation including the multi-dimensional voice program for acoustic analysis, the GRBAS scale for perceptual analysis, and the evaluation of the voice handicap index (VHI) for psychosocial analysis. In total, 68 patients who had undergone STN-DBS (37 assessed in the on- and off-stimulation conditions) and 40 who had been treated with medical therapy alone were evaluated. Further, we performed laryngoscopic examinations in 13 STN-DBS and 19 medical-therapy-alone patients. The STN-DBS group, especially females, showed widespread impairment of voice parameters and significantly poorer VHI scores than the medical-therapy-alone group. The degree of voiceless (DUV) and strained voice were the most impaired factors in the STN-DBS group; and DUV significantly improved after stopping stimulation. Furthermore strained voice, breathiness, and asthenia improved after stopping stimulation. Laryngoscopic examination showed that abnormal laryngeal muscle contraction and incomplete glottal closure were more prominent in the STN-DBS group than in the medical-therapy-alone group. We demonstrated that (1) more widespread voice impairment in females, (2) poorer voice-related QOL, (3) worse DUV and strained voice, and (4) abnormal laryngeal muscle contraction were the characteristic voice and laryngeal findings in the STN-DBS group compared with those in the medical-therapy-alone group.