In accordance with an embodiment, a defect inspection apparatus includes a charged beam irradiation unit, a detection unit, an energy filter, and an inspection unit. The charged beam irradiation unit generates a charged beam and irradiates a sample including a pattern as an inspection target thereon with the generated charged beam. The detection unit detects secondary charged particles or reflected charged particles generated from the sample by irradiation of the charged beam and outputs a signal. The energy filter is arranged between the detection unit and the sample to selectively allow the secondary charged particles or the reflected charged particles with energy associated with an applied voltage to pass therethrough. The inspection unit applies voltages different from each other to the energy filter and outputs information concerning a defect of the pattern from an intensity difference between signals obtained under application voltage different from each other.