The purpose of this experiment was to examine the relationship between prefrontal cerebral blood flow and questionnaire responses during personality self-rating. Participants were 61 university students experimented between May and December 2023. Frontal cerebral blood flow was measured with nIR-HEG under six conditions: three computer-based self-rating tasks, two questionnaire-based tasks, and one eyes-closed baseline. Personality trait scores were obtained using the Big Five, BIS/BAS, and POMS2, and correlation coefficients were calculated between these scores and frontal cerebral blood flow under each condition. To investigate changes in blood flow during personality self-rating, the means and standard deviations of cerebral activity were computed for each participant across conditions. The nIR-HEG index was calculated as the ratio of oxyhaemoglobin (mol / micro L) to deoxyhaemoglobin (mol / micro L), measured with near-infrared and red visible light. The displayed measurement value was 200 times this ratio, producing a unitless nIR-HEG index (Serra-Sala et al., 2012). To explore inter-individual variability in blood flow, cluster analysis was conducted using Ward's method with case-wise standardisation and Euclidean distance. Four clusters were identified, suggesting that individual differences in frontal cerebral blood flow during self-rating could be classified into four distinct patterns. The ANOVA was then performed to examine the relationship between these clusters and personality questionnaire scores. Significant differences were found in Big Five scores for F (F(3,55) = 3.34, p < .05) and Att (F(3,55) = 4.11, p < .05). No significant difference was observed for BIS (F(3,55) = 2.13, n.s.), but BAS scores differed significantly (F(3,55) = 3.25, p < .05). Overall, the findings suggest that personality can be classified according to intra-individual differences in self-rating, and that certain personality traits may influence the degree of curiosities for performance.