To provide a probe cover having excellent elasticity and softness in order to put on and take off easily and to prevent a subject from being infected with virus or bacteria.

This device is made of deproteinized natural rubber and comprises opening 2 on one end and a long closed sack on the other end 3 which has sensor contacting part 4 formed to fit the shape of the sensor on the tip of the probe. Providing a hydrophilic property polymer layer such as polyvinyl alcohol resin and so forth with the inner surface of probe cover 1 reduces friction in installing this device in the probe and allows smooth insertion in the probe.