Aging has been progressing rapidly worldwide. Therefore, it is important to investigate age-related differences in disease pathogenesis to develop age-appropriate treatment plan and drug regimen. In this study, we investigated age-related changes in immune function and pathogenesis in a mouse model of asthma. We compared the quantitative and functional changes of various immune cells in untreated or asthma-induced mice between 10-weeks-old (normal group) and 80-weeks-old (aging group) C57BL/6N mice. A mouse model of asthma was generated by repetitive intranasal administration of Dermatophagoides farina. In untreated mice, naive CD4 and CD8 T cells were significantly decreased in the aging group compared with the normal group, whereas effector CD4 and CD8 T cells and regulatory T cells were significantly increased in the aging group compared with the normal group. In a mouse model of asthma, the pathogenesis of asthma was significantly attenuated compared with the normal group based on the result of percutaneous arterial oxygen saturation (SpO₂). In addition, the aging group showed a significant decrease in type 2 innate lymphocytes and eosinophil counts. Our findings indicate that significant downregulation of immune function in the aging group attenuated the pathogenesis of asthma.