A mounting structure for electric oil pump is provided to allow the electric oil pump to be mounted without through a communication pipe. The electric oil pump includes a pump unit having an inscribed gear pump, and a motor unit disposed adjacent to the pump unit and having a sensorless brushless DC motor for rotating the inscribed gear pump. A transmission accommodates the electric oil pump and includes a transmission case having an oil pan. The electric oil pump is attached to the transmission case with at least a through hole for supplying working oil to the pump unit being submerged in the working oil reserved in the oil pan.