This study has researched on psychological and steroid hormonal effect upon junior-high school students through school music lesson: 1. Music listening, 2. Choir singing. The result showed a significant decrease in cortisol. The study also had conducted a survey about participants' musical preference and their stress level (STAIC – II), which resulted that higher the stress level, more musical activity was willingly conducted. These outcomes suggest that school music lessons can lessen students' stresses and frustrations. Although in developed countries such as Japan, the raison d' être of school music lessons has been questioned recently, the result of this research has shown a new perspective where music lesson can be used as a stress management.