A rubber composition that can improve in good balance the fuel economy, wet-grip performance, and abrasion resistance, and a pneumatic tire that uses this rubber composition are provided. This rubber composition contains a rubber component, and carbon black and/or silica, wherein based on 100% by mass of the rubber component, the rubber component contains 5 to 50% by mass of natural rubber, 0.3 to 10% by mass of an epoxidized natural rubber, and at least 5% by mass of a conjugated diene polymer that has a constituent unit based on a conjugated diene and a constituent unit represented by formula (I) below, at least one terminal of the polymer being modified, and wherein a total content of the carbon black and the silica is 3 to 100 parts by mass per 100 parts by mass of the rubber component.