A motor control device for construction machinery comprising: a hydraulic pump; a hydraulic motor driven by pressure oil from the hydraulic pump; a control valve that controls a flow of the pressure oil from the hydraulic pump to the hydraulic motor; a pair of main conduit lines (L1, L2, L3, L4) that connect the hydraulic motor and the control valve on a delivery side and a return side thereof; and an operation member that operates a spool of the control valve to either a neutral position that does not allow the pressure oil for driving from the hydraulic pump to pass through the control valve to the hydraulic motor or a non-neutral position (R, F) that allows the pressure oil for driving to pass through the control valve to the hydraulic motor, wherein a counterbalance valve having a diaphragm functioning as a braking pressure generating device that generates braking pressure in the main conduit lines on the return side in a state where the spool of the control valve is positioned in the neutral position as a result of being operated by the operation member, the braking pressure opposing rotation of the hydraulic motor; and characterized by a flow control device for allowing the pressure oil from the hydraulic pump to flow into the pair of main conduit lines (LI, L2, L3, L4) while the braking pressure is generated by the braking pressure generating device, and the flow control device having a hydraulic directional valve, and the pressure oil from the hydraulic pump being guided to the pair of main conduit lines (L1, L2, L3, L4) via the directional valve without passing via the control valve, and the flow control device further having: a pilot check valve; a solenoid operated directional valve; and a hydraulic power source for supplying pilot pressure for acting on the hydraulic directional valve and the pilot check valve, wherein pilot ports of the hydraulic directional valve and the pilot check valve are connected to the solenoid operated directional valve. a hydraulic pump; a hydraulic motor driven by pressure oil from the hydraulic pump; a control valve that controls a flow of the pressure oil from the hydraulic pump to the hydraulic motor; a pair of main conduit lines (L1, L2, L3, L4) that connect the hydraulic motor and the control valve on a delivery side and a return side thereof; and an operation member that operates a spool of the control valve to either a neutral position that does not allow the pressure oil for driving from the hydraulic pump to pass through the control valve to the hydraulic motor or a non-neutral position (R, F) that allows the pressure oil for driving to pass through the control valve to the hydraulic motor, wherein a counterbalance valve having a diaphragm functioning as a braking pressure generating device that generates braking pressure in the main conduit lines on the return side in a state where the spool of the control valve is positioned in the neutral position as a result of being operated by the operation member, the braking pressure opposing rotation of the hydraulic motor; and characterized by a flow control device for allowing the pressure oil from the hydraulic pump to flow into the pair of main conduit lines (LI, L2, L3, L4) while the braking pressure is generated by the braking pressure generating device, and the flow control device having a hydraulic directional valve, and the pressure oil from the hydraulic pump being guided to the pair of main conduit lines (L1, L2, L3, L4) via the directional valve without passing via the control valve, and the flow control device further having: a pilot check valve; a solenoid operated directional valve; and a hydraulic power source for supplying pilot pressure for acting on the hydraulic directional valve and the pilot check valve, wherein pilot ports of the hydraulic directional valve and the pilot check valve are connected to the solenoid operated directional valve.