The solid-state convection in the Earth mantle is characterized by plate tectonics, which shapes the tectonic activities of the Earth, and superplumes as broad hot regions chemically distinct from the surrounding regions in deep lower mantle. Recent numerical studies of mantle convection suggest that the rigidly moving plates occur on the Earth because the rupture strength of plate margins is sufficiently low, while that of plate interiors is high enough to inhibit spontaneous formation of new plate boundaries by the weight of the plates themselves. This implies that the activity of plate tectonics has fluctuated much in the Earth history. Recent numerical studies also suggest that the superplumes develop owing to the chemical differentiation of the mantle by ridge magmatism. Superplumes have probably induced frequent and vigorous hot spot volcanism in the early Earth. It is now within reach to construct an integrated model for tectonic and structural evolution of the mantle in the Earth and other terrestrial planets.