The A‐factor receptor protein (ArpA) containing an α‐helix‐turn‐α‐helix DNA‐binding consensus sequence at its N‐terminal portion plays a key role in the regulation of secondary metabolism and cell differentiation in Streptomyces griseus. A binding site forming a palindrome 24 bp in length was initially recovered from a pool of random‐sequence oligonucleotides by rounds of a binding/immunoprecipitation/amplification procedure with histidine‐tagged ArpA and anti‐ArpA antibody. By means of further binding/gel retardation/amplification experiments on the basis of the recovered sequence, a 22 bp palindromic binding site with the sequence 5′‐GG(T/C)CGGT(A/T)(T/C)‐G(T/G)‐3′ as one half of the palindrome was deduced as a consensus sequence recognized and bound by ArpA. ArpA did not bind to the binding site in the presence of its ligand, A‐factor. In addition, exogenous addition of A‐factor to the ArpA–DNA complex induced immediate release of ArpA from the DNA. All of these data are consistent with the idea, obtained from previous genetic studies, that ArpA acts as a repressor‐type regulator for secondary metabolism and cellular differentiation by preventing the expression of a certain key gene(s) during the early growth phase. A‐factor, produced in a growth‐dependent manner, releases ArpA from the DNA, thus switching on the expression of the key gene(s), leading to the onset of secondary metabolism and aerial mycelium formation.