The surface of cross-linked rubber gives a sticky touch in general. Its frictional coefficient is quite high and very sensitive to velocity and temperature, in addition to generating stick-slip motion and Schallamach wave during frictional sliding. Similar behaviors are also observed in gel and uncross-linked rubber, which seems to indicate that a meniscus is formed in common on the surface of these materials in frictional sliding. Such a component spreading over a surface of cross-linked rubber may be an uncross-linked rubber phase, which governs the friction and wear of cross-linked rubber.