Swallowing disorders are common in the elderly, and aging is a factor that affects swallowing function. The elevation of the hyoid bone is important for swallowing and is controlled by the suprahyoid muscles. The hyoid and laryngeal elevation allows the bolus to enter the esophagus. The suprahyoid muscles, therefore, play an important role in swallowing. The effects of aging on suprahyoid muscle strength are unclear. In this study, we analyzed the effects of aging on suprahyoid muscle strength by comparing the jaw opening functions of healthy adults and elderly adults. The subjects were 150 healthy volunteers consisting of 76 adults aged < 70 years (38 men and 38 women; mean age, 48.8 ± 13.8 years; range, 23-69) and 74 elderly adults aged > 70 years (37 men and 37 women; mean age, 78.1 ± 4.8 years; range, 70-92). The jaw opening force (JOF) was measured with a jaw opening sthenometer and compared between the healthy adult and elderly groups. The mean JOF of healthy adults was about 10 kg in men and about 6 kg in women, which was significantly greater than the mean JOF of the healthy elderly subjects (about 7 kg in men and about 4 kg in women). The JOF of the men was significantly greater than that of the women in the healthy adult and elderly groups. We thus propose that aging decreases the strength of suprahyoid muscles in healthy adults. The swallowing function may decrease even in healthy adults, aged over 70 years.