While kindergarten teachers have shown resilience under adverse work environment, scarce empirical research has examined these teachers’ resilient protective factors, namely hardiness and optimism. The study had two aims. First, it examined the correlation relationships among variables of hardiness, optimism, self-esteem, and mental health complaints. Second, it testified the mediating effect of hardiness on optimism. Inservice kindergarten teachers were invited to participate in the study as voluntary convenient samplings. They were asked to complete four inventories anonymously to enhance confidentiality and their willingness to participate. Eventually, 64 out of 104 teachers participated and returned the inventories. Results showed that both hardiness and optimism correlated positively with self-esteem but negatively with mental health complaints. While hardiness mediated the effects of optimism, teachers’ commitment (a subscale of hardiness scale) appeared to predict consistently their self-esteem and mental health complaints. Implications of rethinking optimism and promoting teachers’ resilience through hardiness training are discussed.