The present invention provides a composition capable of regulating the activity of autonomic nerves, by acting on these nerves, so as to maintain the homeostasis or alleviate disturbed homeostasis in an animal, wherein the above composition can be obtained from a naturally occurring substance in the nature by a simple process. The seawater mineral-containing composition of the present invention is characterized in that it contains seawater minerals obtained by treating seawater and is capable of regulating autonomic nerves. The seawater mineral-containing composition of the present invention preferably has a magnesium concentration of 70 mg/L or higher and a sodium concentration of 3 mg/L or lower.