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Haspin is a unique protein kinase expressed predominantly in haploid male germ cells. The genomic structure of haspin (Gsg2) has revealed it to be intronless, and the entire transcription unit is in an intron of the integrin alphaE (Itgae) gene. Transcription occurs from a bidirectional promoter that also generates an alternatively spliced integrin alphaE-derived mRNA (Aed). In mice, the testis-specific alternative splicing of Aedis expressed bidirectionally downstream from the Gsg2transcription initiation site, and a segment consisting of 26 bp transcribes both genomic DNA strands between Gsg2and the Aedtranscription initiation sites. To investigate the mechanisms for this unique gene regulation, we cloned and characterized the Gsg2promoter region. The 193-bp genomic fragment from the 5′ end of the Gsg2and Aedgenes, fused with EGFPand DsRedgenes, drove the expression of both proteins in haploid germ cells of transgenic mice. This promoter element contained only a GC-rich sequence, and not the previously reported DNA sequences known to bind various transcription factors—with the exception of E2F1, TCFAP2A1 (AP2), and SP1. Here, we show that the 193-bp DNA sequence is sufficient for the specific, bidirectional, and synchronous expression in germ cells in the testis. We also demonstrate the existence of germ cell nuclear factors specifically bound to the promoter sequence. This activity may be regulated by binding to the promoter sequence with germ cell-specific nuclear complex(es) without regulation via DNA methylation.