Essential oils have potential biological effects, i.e., antibiotic, anticarcinogenic, and sedative effects during stress. In the present study, we investigated the antibacterial and antifungal effects of essential oils extracted from the coniferous species Pinus densiflora, Pinus koraiensis, and Chamaecyparis obtusa, because their biological activities have not been yet elucidated. The essential oils were quantified using gas chromatography and identified in gas chromatography-mass spectrometric analysis. Simultaneously, antibacterial and antifungal assays were performed using the essential oils distilled from the needles of coniferous trees. The major components and the percentage of each essential oil were: 19.33% beta-thujene in P. densiflora; 10.49% alpha-pinene in P. koraiensis; 10.88% bornyl acetate in C. obtusa. The essential oils from P. densiflora and C. obtusa have antibacterial effects, whereas essential oils from P. koraiensis and C. obtusa have antifungal effects. These results indicate that the essential oils from the three coniferous trees, which have mild antimicrobial properties, can inhibit the growth of gram-positive and gram-negative bacteria and fungi.