Only a few studies have examined the relationship between self-assessment of affective symptoms and brain activation in a non-clinical population. The aim of the present study was to assess this relationship and examine the underlying cortical mechanisms in a non-clinical population. Seventy-nine healthy male volunteers were assessed for affective symptoms using the Zung Self-rating Depression Scale (SDS), for apathy using the Apathy Scale (AS), and for feelings of stress using the Stress Arousal Checklist (SACL). Participants also performed a serial arithmetic task according to the Uchida-Kraepelin performance test while hemoglobin concentration changes were assessed on the surface of the prefrontal cortex (PFC) using 32-channel near-infrared spectroscopy (NIRS). The activity on the right side of PFC had a significant negative correlation with the SDS score. The AS and SACL scores were positively correlated with the SDS score. Furthermore, in a multiple regression analysis, SDS scores were predicted by the activity of the right PFC, AS scores, and SACL scores. These results suggest that the association between the cortical activation changes, apathy, and feelings of stress may objectively identify individuals with sub-threshold affective symptoms.