Provided are a machining device and a machining method in which machining of higher precision can be performed with a simple configuration. The machining device has an irradiation head (16) and a controller; the irradiation head (16) has a laser revolving unit (35) and a light collection optical system (37); and the laser revolving unit (35) has a first prism (51), a second prism (52), a first rotation mechanism (53), and a second rotation mechanism (54). The controller adjusts the rotational speeds and the difference in phase angles of the first prism (51) and the second prism (52), on the basis of at least the relationship between a heat affected layer of a member to be machined and the revolving speed of the laser.
