Despite the fact that the lifetime and yearly prevalence rates of mental illness continue rising, such diseases have only been acknowledged as involved in workplace health issue since the 2000s. Additionally, while the number of recognized cases of mental illnesses is rather low compared to their prevalence, they have a high likelihood of causing significant problems, including fatalities. Many workers are terrified of losing their jobs due to mental illness and therefore attempt to hide their mental health problems. For this reason, clinicians involved in occupational and environmental medicine should focus on interviews or screenings to identify such hidden mental health problems. More specifically, it would be helpful to evaluate job stress and depression in workplaces to ensure appropriate preventive actions and thereby reduce the prevalence of mental illness. Job stress not only causes mental illness and dissatisfaction with work, but also can increase the prevalence and morbidity of medical diseases, as well as other physical health problems. Depression is a major contributor to work loss and absence with effects surpassing almost all of the chronic medical disorder. These facts show why measure of job stress and depression should be highlighted in the occupational settings. This article introduces a variety of assessment tools to examine mental health, particularly stress and depression, in workplaces. These tools can be used by clinicians or professionals involved in the mental health, occupational safety, or health service fields for running diagnostics or screening tests.