The present invention relates to a chuck mechanism of a charge-discharge test device for a thin secondary battery, and aims to provide a chuck mechanism having excellent action controllability. The chuck mechanism includes: a chuck drive part which is movable in a direction toward a battery container housing a thin secondary battery; and a chuck activation part which is located away from the chuck drive part in the direction toward the battery container and whose movement in the same direction is restricted. In the chuck mechanism, when the chuck unit is moved in the direction toward the battery container, the chuck drive part activates a chuck member of the chuck activation part whose movement in the same direction is restricted.