A study on workflow system as an automated business processing system is done recently. However, it did not consider various dependencies between parallel tasks. Therefore, this paper proposes modeling and verification of workflows with various parallel dependencies. For this, firstly, we propose four dependencies to specify various parallel dependencies between tasks. They contain sequential starts, parallel starts, sequential commits, and parallel commits. Secondly, we suggest a method to specify various parallel dependencies on workflow graph. Thirdly, we propose a verification method to detect contradictions on workflow specifications.