BPMN (Business Process Model and Notation) models are used to specify business knowledge in the language that is familiar for business people. They consist of multiple process diagrams that highlight different aspects of interaction among participants. Verification of BPMN models is important since graphical fragmentary presentation could be a source of errors such as incompleteness, deadlocks, livelocks, incorrect terminations etc. We consider verification of model completeness. The model is transformed to the topological functioning model (TFM) in order to check completeness of inputs, outputs and functioning cycles of the entire specified system. The proposed approach is dedicated to the verification of the model at the beginning of analysis, and it could be supplemented by other methods at the design stage. This approach is more dedicated to analysis of the whole system, than to the verification of the concrete fragment work.