Recently, high-density deployment of mmWave small cell base stations has been focused as a means to cope with the rapidly increasing mobile data traffic. MmWave overlay heterogeneous network (HetNet) is proposed to realize eMBB, however laying cost of backbone utilizing high-capacity optical fibers is very costly to support ultra- broadband accesses. On the other hand, Multi- access Edge Computing (MEC) is proposed to reduce mobile data traffic on backhaul networks. MEC deploys contents requested by User Equipment (UE) nearby in advance based on registered context information e.g. location, destination, and required contents to the orchestrator. Therefore, it is possible to utilize mmWave access under existing backhaul networks by introducing prefetching algorithm. The architecture is enabled by wireless Software Defined Network (SDN) technology. In this paper, Proof-of-Concept (PoC) architecture is proposed, and the effectiveness of mmWave HetNet with MEC utilizing prefetching algorithm is confirmed by measuring the download time of real content.