Abstract. A real-world labor market has complex worksite interactions between a worker and an employer. This paper investigates the behavior patterns of workers and employers with a job capacity and a job concentration empirically considering a strategic coalition in an agent-based computational labor market. Here, the strategic coalition can be formed autonomously among workers and/or among employers. For each experimental treatment, the behavior patterns of agents are varied with a job capacity and a job concentration depending on whether a coalition is allowed. Experimental results show that a strategic coalition makes workers and employers aggressive in worksite interactions against their partners.