An apparatus and a method for detecting phase deficiency in an inverter is provided, the method including deciding whether a sector of the output current is a sector where current detection is possible based on switching operation status of the switching element in the inverter, maintaining a phase deficiency variable when deciding the current detection in the sector of the output current to be impossible, adding a count to a phase deficiency variable to accumulate when deciding the current detection in the sector of the output current to be possible and deciding the output current to be within a phase deficiency band, and determining as phase deficiency when the phase deficiency variable is greater than a prescribed detection level.