To obtain a crude liquefaction oil from coal while attaining a high liquid space velocity and a high heat efficiency based on double heat insulation.

A pasty mixture of a fine coal powder, a catalyst, and a heavy oil is heated at a high temp. in a hydrogen atmosphere to hydrocrack and thus liquefy the coal. This direct coal liquefaction is conducted using a continuous reactor comprising cylindrical reaction vessels connected to each other, which comprise the first cylinder of nearly perfect mixing type and plug flow type cylinders comprising the second and the final cylinders. Each cylinder has a heat coil at the center, a double heat insulation surrounding the heat coil and disposed on the inner and outer walls of the cylinder, and a heat exchange zone between the two insulation layers. Each cylinder comprises the first inner tube and the second inner tube. The second inner tube is provided at its center with a heat coil and a straight tube for feedstock supply. Hydrogen is introduced from the uppermost part of the heat coil, and the hydrogen heated to a high temp. is bubbled into the pasty mixture in the lowermost part of the heat coil to heat and hydrogenate the mixture.