Background Job training influences the overall working environment and worker's well-being. The purpose of this study is to find the relationship between job training and subjective well-being in accordance with occupations and understand the influence of task characteristics—work creativity and task variety (WCTV)—on the effect of training. Methods A cross-sectional study based on the Fifth Korean Working Conditions Survey was conducted on 50,205 workers in the Republic of Korea. The World Health Oorganization–5 well-being index was used to measure their subjective well-being. The relationship between job training and subjective well-being was divided in accordance with the level of WCTV. Results Training paid for by employer showed a negative effect on subjective well-being when received for more than 3 days (OR 0.88, p < 0.01) in the last 12 months. Training paid for by oneself showed a positive linkage with well-being when the level of training was 1–3 days (Odds ratio = 1.55, p < 0.001). This result showed different aspects in accordance with the level of WCTV. For the high WCTV group, the aforementioned results were reaffirmed, but for the group with low WCTV, job training did not show a statistically significant result on well-being. On-the-job training was not related to subjective well-being regardless of the level of WCTV. Conclusion Job training had different effects on subjective well-being depending on the type and frequency of training, as well as the WCTV. It is imperative to comprehensively apply different types of job training in accordance with the characteristics of occupations to uplift workers' well-being.