Pseudomonas aeruginosa is an opportunistic pathogen and sometimes cause severe lung or systemic infection in the compromised host. It produces many pathogenic factors, such as toxins and degrading or tissue damaging enzymes in the infection loci. Most of these proteins and virulence factors are expressed only in the stationary phase and not in the exponential-growing phase, so the bacterial cells are not recognized during colonization as a threat by the host defense systems.  There are many studies about stationary phase-specific gene regulations in P. aeruginosa. In this article, we will summarize the recent studies about such gene regulation mechanisms, σ^S and cell-density dependent or ‘Quorum sensing’ systems and present some evidences that there is the novel unknown mechanism of stationary phase-specific gene regulation in P. aeruginosa.