Optical device and article manufacturing method

An article manufacturing method, comprising:

• processing a subject using an optical device which processes the subject by irradiating the subject with laser light;
• and
• processing the subject which has been subjected to the processing in the step, wherein the optical device includes:
• a focal position adjustment mechanism configured to adjust a focal position of laser light;
• an incident position adjustment mechanism configured to adjust an incident position of the laser light incident on the subject in a direction perpendicular to a focal direction of the laser light;
• and
• a control unit configured to control driving of the focal position adjustment mechanism and the incident position adjustment mechanism,
• wherein the control unit controls the driving of the incident position adjustment mechanism based on an amount of driving of the focal position adjustment mechanism to correct a shift of the incident position due to the change of the focal position.