Drosophila melanogaster males display stereotypical courtship ritual in courting potential mates. The fruitless (fru) gene plays a pivotal role in the generation of male-typical courtship behavior by instructing the formation of the central circuitry underlying this behavior during development. The fru gene expression can be monitored by a reporter, fruNP21, that labels approximately 800 neurons in the adult male brain. Among these fru-expressing neurons, a male-specific neural cluster called P1 initiated male-typical courtship behavior; when the P1 cluster was ectopically produced in the female brain, many such females displayed male-typical courtship behavior toward a target female. To further elucidate the central circuitry for courtship behavior, we examined central projections of sensory neurons that appear to perceive sex pheromones sensed in the foreleg gustatory receptors. The central terminals of these sensory neurons are located near dendrites of the fru-expressing interneurons named mAL. These results suggest that different subsets of fru-expressing neurons are involved in both the sensory integration of sexual cues and the activation of motor centers that generate motor outputs for courtship behavior in the Drosophila brain.