Dogs show high social communicative ability in interactions with humans. We investigated the association between dogs’ social communicative behavior and the polymorphisms of a gene related to a neurotransmitter. We used an “unsolvable task”, in which an experimenter put a food reward into a container and closed it firmly so that dogs could not remove the reward. Human-directed gazing, possibly to request help, is a characteristic behavioral trait of dogs in such situations. The association between owner-directed gazing behavior in the unsolvable task and polymorphisms of three regions (exon1, exon3, intron2) in the dopamine receptor D4 gene (DRD4) was analyzed. We found that the genotype of DRD4 intron2 was significantly associated with the dogs’ gazing behavior. Dogs carrying shorter allele (P) looked at their owner more frequently, for longer, and earlier than dogs carrying longer allele (Q). This result suggests that polymorphism in DRD4 intron2 may affect social communication and cognition in dogs.