The purposes of this research were to study the level of mental health power and selected factors related to mental health power of nursing undergraduate students, Srimahamarakham Nursing College. The sample consisted of 91 first-year nursing undergraduate students at Srimahasarakham Nursing College, Faculty of Nursing, Praboromarajhanok Institute who were selected by purposive sampling. The research tool was the mental health power assessment questionnaire. The statistics used for data analysis were frequency, percentage, mean, standard deviation and the spearman's correlation coefficient. The results showed that the mean of overall mental health power was lower than the criteria ([x-bar]= 57.64). When considering mental health power on each aspect, it was found that emotional stability [x-bar]= 28.98, encouragement [x-bar] = 13.81 and problem management [x-bar] = 14.84 which is below the threshold level on all aspects. And factors that had a positive correlation with the mental health power of nursing undergraduate students statistical significance (p< 0.05). There was also a moderate correlation (r = 0.04) were associated homeland low level (r = 0.01) and monthly income had a moderate relationship (r = 0.03). The factors that did not relate with the mental health power of nursing undergraduate students were gender (r = 0.10) and the order of siblings or their children (r = 0.09).