Rubber composition, method of producing the same and tire using the same

A rubber composition comprises a diene rubber component, a filler and a softening agent, in which a given amount of a filler is compounded based on 100 parts by mass of a diene rubber component, and a softening agent is included in a given amount per the filler, and not less than 60% by mass of the diene rubber component is a solution-polymerized styrene-butadiene copolymer rubber having a mass average molecular weight of not less than 1,000,000, and the filler is selected from the group consisting of carbon black, silica and an inorganic agent of a formula (I): mM . xSiOy . zH2O (wherein M is at least one metal selected from the group consisting of aluminum, magnesium, titanium and calcium, or an oxide of such a metal or a hydroxide of such a metal, m is a number of 1-5, x is a number of 0-10, y is a number of 2-5 and z is a number of 0-10), wherein each of the filler and the softening agent is charged in at least two fractions.