The performance of tank devices, such as porous metals and a metal fiber, on liquid propellant retention was evaluated under microgravity environment. IKAROS carries the gas-liquid equilibrium propulsion system which stores propellant as liquid phase in a storage tank and expels only gaseous propellant from the tank. Surface tension in pores of tank devices holds liquid propellant in them. As a result of microgravity experiments, it was found that the performance on liquid retention is higher than that estimated from results of bubble point experiment, and it strongly depends on the existence of bubbles in liquid propellant. From the results of the experiment, this paper proposes the location of porous metals in the storage tank to prevent bubbles from remaining with propellant consumption.