Carbon black-containing composite resin pre-expanded particles comprising 100 to 400 parts by mass of a polystyrene-based resin with respect to 100 parts by mass of a carbon black-containing polyolefin-based resin; having a carbon black content of 0.5 to 5.0% by mass and a bulk density of 0.015 to 0.25 g/cm 3; and having an outermost layer of 30 to 80 μm after undergoing the following tests: (a) one of the carbon black-containing composite resin pre-expanded particles is sliced into a 1-mm slice in such a way that cross-section surfaces of cells are exposed on both surfaces of the slice; (b) the obtained slice is immersed in toluene at 25°C for 24 hours to extract a polystyrene-based resin component as described above; (c) the cross-section surface of the slice is then subjected to magnified photographing by a microscope; (d) the obtained microscope image is observed; wherein the particles are obtainable by a method comprising the successive steps of: obtaining a suspension by dispersing carbon black-containing polyolefin-based resin particles in an aqueous medium comprising a dispersant; adding a styrene-based monomer and a polymerization initiator to the obtained suspension, heating the mixture to a temperature that does not substantially allow polymerization of the styrene-based monomer, and immersing the styrene-based monomer in the carbon black-containing polyolefin-based resin particles to obtain a reaction solution; heating the obtained reaction solution to temperatures of (T - 10)°C to (T + 20)°C, in which T °C indicates a melting point of a polyolefin-based resin in the carbon black-containing polyolefin-based resin particles, the melting point being determined according to "Testing Methods for Transition Temperatures of Plastics" of JIS K7121-1987, in accordance with the section "Melting point (°C)" of the specification, so as to polymerize the styrene-based monomer, and repeating these processes, so that the polymerization is carried out three times or more and the styrene-based monomer content used in each polymerization is kept low, to obtain carbon black-containing composite resin particles; immersing a blowing agent in the obtained carbon black-containing composite resin particles to obtain expandable carbon black-containing composite resin particles; and heating and pre-expanding the obtained expandable carbon black-containing composite resin particles in a reaction vessel by introducing a gauge pressure 0.004 to 0.09 MPa of steam so as to obtain carbon black-containing composite resin pre-expanded particles. (a) one of the carbon black-containing composite resin pre-expanded particles is sliced into a 1-mm slice in such a way that cross-section surfaces of cells are exposed on both surfaces of the slice; (b) the obtained slice is immersed in toluene at 25°C for 24 hours to extract a polystyrene-based resin component as described above; (c) the cross-section surface of the slice is then subjected to magnified photographing by a microscope; (d) the obtained microscope image is observed; obtaining a suspension by dispersing carbon black-containing polyolefin-based resin particles in an aqueous medium comprising a dispersant; adding a styrene-based monomer and a polymerization initiator to the obtained suspension, heating the mixture to a temperature that does not substantially allow polymerization of the styrene-based monomer, and immersing the styrene-based monomer in the carbon black-containing polyolefin-based resin particles to obtain a reaction solution; heating the obtained reaction solution to temperatures of (T - 10)°C to (T + 20)°C, in which T °C indicates a melting point of a polyolefin-based resin in the carbon black-containing polyolefin-based resin particles, the melting point being determined according to "Testing Methods for Transition Temperatures of Plastics" of JIS K7121-1987, in accordance with the section "Melting point (°C)" of the specification, so as to polymerize the styrene-based monomer, and repeating these processes, so that the polymerization is carried out three times or more and the styrene-based monomer content used in each polymerization is kept low, to obtain carbon black-containing composite resin particles; immersing a blowing agent in the obtained carbon black-containing composite resin particles to obtain expandable carbon black-containing composite resin particles; and heating and pre-expanding the obtained expandable carbon black-containing composite resin particles in a reaction vessel by introducing a gauge pressure 0.004 to 0.09 MPa of steam so as to obtain carbon black-containing composite resin pre-expanded particles.