Biological factors influencing exploratory behavior were investigated in 80 litters of CD-1 control mice in two-generation toxicity studies. Litter size and sex ratio were measured at birth [postnatal day (PND) 0], while offspring body weight were measured on PND 0 and 21 during the lactation period. Offspring were examined for exploratory behavior at three weeks of age. After weaning, mice were weighed and examined for exploratory behavior at eight weeks of age. The relationships between biological factors and exploratory behavior were assessed with canonical correlation analysis at three and eight weeks of age in the F₁ generation. Litter size at birth, secondary sex ratio (male%), body weight (g) at birth, and body weight (g) at the time of examination were used as explanatory data, and exploratory behavior variables were used as response variables. After canonical correlation analysis, variables having a significant axis in coefficient of structure were assessed with multiple regression analysis. In female offspring, body weight at the time of examination showed a positive effect (coefficient of determination R² = 0.559) on vertical time (sec) at three weeks of age. Therefore, it is necessary to observe the changes in vertical time in relation to body weight in immature females.