Background: Society is rapidly aging worldwide, and the incidence of chronic respiratory disease is increasing. Because spirometry requires specialized equipment and is not widely available, a technique that can easily and objectively evaluate pulmonary function is needed. Methods: A total of 76 participants enrolled in the present study (29 in the healthy older group and 47 in the respiratory disease group). Pulmonary function data obtained with a conventional spirometer were compared with that obtained with a simple expiratory pressure measurement device. Results: Significant differences in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow, and integration expiratory pressure were found between the groups. Strong correlations between integration expiratory pressure and FVC and between integration expiratory pressure and FEV1 were noted in all participants. Conclusions: The integration expiratory pressure values obtained by the simple expiratory pressure measurement device approximated the participants' FVC values from spirometry, suggesting that integration expiratory pressure values can predict decreases in FVC.