1. A defect inspection device, comprising: an illumination optical system that irradiates a sample with a light or an electron beam; a detector that detects a signal obtained from the sample by irradiation with the light or the electron beam; a defect detecting unit that detects defect candidates on the sample by comparing a signal output from the detector with a predetermined threshold; and a display unit that displays a setting screen for setting the threshold, wherein the setting screen is a two-dimensional distribution diagram that represents a distribution of defect candidates in a three-dimensional feature space with three features as axes and includes the axes of three features and the threshold represented in one dimension.