The purpose of the present invention is to provide a visibility-ensuring material which is capable of ensuring a surgical field for a fixed time period, which does not inhibit the transmission of light, and which is capable of ensuring visibility with which even delicate operations can be satisfactorily performed. This visibility-ensuring material includes a gel-like viscoelastic body, and has a storage elastic modulus during use of 40-700 Pa. Furthermore, this device for discharging the visibility-ensuring material includes at least at least one member selected from the group consisting of a syringe, a mesh filter, a needle, and an application nozzle.
