PROBLEM TO BE SOLVED: To provide a technique capable of grasping an amount of activity conveniently and intuitively.SOLUTION: An activity meter 1 comprises: an amount-of-activity detection body 10 including a first fluid phase 101 and a second fluid phase 102 that is phase-separated from the first fluid phase 101 at use temperature and an exterior body 20 that seals the amount-of-activity detection body 10 and has a visual recognition area for visually recognizing the amount-of-activity detection body 10 from the outside. By activity, the first fluid phase 101 and the second fluid phase 102 are mixed together, and the mixed state can be visually recognized from the outside.
