To provide a diene-based rubber composition suitably usable as a vulcanized molded material such as a bead insulation rubber, a bead core-covering rubber, etc., used for forming a part of the bead core part of a pneumatic tire.

This diene-based rubber composition is obtained by blending by the blending amount of 140 to 180 pts.wt. in total of bituminous coal pulverent, carbon black and fillers other than these, including 5 to 38 pts.wt. bituminous coal pulverent based on 100 pts.wt. diene-based rubber. In the diene-based rubber composition, the viscosity of unvulcanized rubber composition is decreased, which decides its processability and also to improve its hardness and tensile elongation at break by replacing a certain amount of the added fillers with the bituminous coal pulverent to make the total blending amount of the bituminous coal pulverent, carbon black and the other fillers as a constant amount.