An apparatus for delay angle compensation for flying start function in a medium-voltage inverter is disclosed. The apparatus generates generate a phase angle (θ) by converting a three-phase voltage of an inverter output terminal to dq-axis voltages (Vd, Vq), and calculate a compensation phase angle by a predetermined delay time. In addition, the apparatus generates an initial angle for the flying start by aggregating the compensation phase angle with the phase angle (θ). The apparatus may drive a high-voltage motor more stably, because an error between a command voltage phase angle and an actual output voltage phase angle may be reduced, when electric power of the medium voltage inverter is restored after a trip or an instantaneous blackout occurs.