Disclosed is a machine learning device of a cutting condition adjustment apparatus including: a state observation section that observes, as state variables indicating a current state of an environment, cutting condition data indicating a laser cutting condition for a laser cutting and oblique rearward temperature rise data indicating a temperature rise value at an oblique rearward part of a cutting front of a workpiece, a determination data acquisition unit that acquires temperature rise value determination data for determining propriety of the temperature rise value during cutting based on the laser cutting condition for the laser cutting as determination data indicating a propriety determination result of the cutting of the workpiece, and a learning unit that learns the temperature rise value and adjustment of the laser cutting condition for the laser cutting in association with each other using the state variables and the determination data.