Provided is a microscope and an observation method which can improve spatial resolution. A microscope according to an aspect of the invention includes a laser light source (10), an objective lens (16) that focuses light from the laser light source on a sample, and a detector (22) that detects the laser light as signal light from a sample (17) when the sample (17) is irradiated with the laser light. The light is applied to the sample with an intensity changed to obtain a nonlinear region where intensities of the light and the signal light have a nonlinear relation due to occurrence of saturation or nonlinear increase of the signal light when the light has a maximum intensity, and the detector (22) detects the signal light according to the intensity of the laser light to perform observation based on a saturation component or a nonlinear increase component of the signal light.