This study presents the new dispatching rules of job shop scheduling with unbalanced machine workloads to decrease mean flow time and mean tardiness. The proposed dispatching rules consider the information related to work remaining, modified job due dates, modified operation due dates and machine workload. The performance of the new dispatching rules is compared and analyzed with the existing rules through the computer simulation at different levels of workload imbalanced. The results can be useful to the researchers and practitioners of job shop scheduling with unbalanced machine workloads.