The melting relation of iron-carbon system is studied to see how iron takes in or disgorges carbon at high pressure (up to 12 GPa). The understanding on these points is closely related to the problem of the reservoir of carbon in the earth's interior. The results are: (1) Iron-carbon system shows eutectic melting till at least 12 GPa. (2) The eutectic composition is about 3 or 4 wt% of carbon, which does not vary very much with pressure. (3) The eutectic temperature slightly goes up as pressure increases at a rate of 7¿C/GPa. This gradient is fairly lower than that of the melting temperature of silicates. Based on these results and other facts, the following scenario is inferred on the core formation during the early stage of the earth. Because carbon melts into iron forming eutectic system at low temperature, carbon within the accreted chondritic materials might be absorbed into iron melt near the surface of the magma ocean. The observation that the melting temperature of silicate goes up more rapidly as pressure increases than the eutectic temperature of iron-carbon system, indicates that the temperature within the magma ocean is maintained higher than the melting temperature of iron-carbon system. Therefore, the carbon-bearing iron melt may sink into the deep interior of the earth without solidifying and disgorging carbon. After all, it is strongly suggested that carbon may settle with liquid iron forming core. ¿ American Geophysical Union 1993