An object is to prevent a bottle from being inclined when a weight is dropped, and to prevent cushion members from moving due to the impact applied when the bottle is inclined, thereby enabling efficient and correct measurement of the water hammer strength. An apparatus for testing the water hammer strength includes holding element that holds bottle filled with content and sealed with a cap at a position above the center of gravity thereof so as to suspend the bottle in the air, and the holding element is placed on cushion members placed on a fixing stage. A weight is then dropped onto the cap to measure the water hammer strength. The cushion members are compressed and deformed in advance using a compression element for forcing the holding element downward to solve the above-described problems.