Measurement of stress hormones is a common objective method for assessment of mental stress. However, the stress of blood sampling alone may also increase stress hormone levels. In the present study, we sampled salivary biomarkers from healthy volunteers under noninvasive conditions and determined their efficacy to assess mental stress. Specifically, we examined the relationship between State Anxiety Inventory score (STAI-s) in subjects exposed to arithmetic stress and salivary chromogranin-A, alpha-amylase, or cortisol. The STAI-s was significantly correlated to salivary alpha-amylase (r = 0.589; P < 0.01) but not to salivary chromogranin-A or cortisol. Therefore, salivary alpha-amylase is a useful indicator of psychosocial stress.