To provide a preparation process of a softener-containing elastomer composition wherein a softener-containing elastomer composition having high mechanical properties is obtained.

In a preparation process of a partially or completely dynamically crosslinked elastomer composition comprising (A) a crosslinkable elastomer, (B) a thermoplastic resin, (C) a softener and (D) a softener retainer, first, (A), (C) and (D) are mixed without melting to prepare a master batch(MB), and subsequently, the MB and (B) are melt kneaded and dynamically crosslinked. Especially, when preparing MB, (E) a crosslinking agent and (F) a crosslinking auxiliary are mixed.