The present invention has its object to provide a rubber composition excellent in low-exothermic property, breaking strength, and crack growth resistance, and a pneumatic tire including at least one of a base tread, a cushion, a carcass and a tie gum that are prepared using the rubber composition. The present invention relates to a rubber composition including: a rubber component which contains (a) 10 to 30% by mass of at least one of a butadiene rubber modified by a compound represented by the formula (1): and a tin-modified polybutadiene rubber resulting from polymerization with a lithium initiator (b) 10 to 40% by mass of a modified styrene-butadiene rubber having a bound-styrene content of 21% by mass or less; and (c) 20 to 80% by mass of a diene rubber other than (a) and (b), and (d) 7 to 50 parts by mass of silica per 100 parts by mass of the rubber component.