1. An image capturing method executed by an image capturing apparatus including an illumination that illuminates a subject, the image capturing method comprising: continuously generating, using a processor, one or more OFF images in which the subject is captured with the illumination turned OFF, for a first number of times; continuously generating, using the processor, ON images in which the subject is captured with the illumination turned ON, for a second number of times; continuously generating, using the processor, one or more OFF images in which the subject is captured with the illumination turned OFF, for the first number of times after capturing the ON images; computing, using the processor, a difference image between each of the generated ON images and an OFF image corresponding to the ON image among the generated OFF images; and integrating, using the processor, the computed difference images, wherein the generating includes turning OFF the illumination and capturing N/2 OFF images before and after N ON images are captured, the N is a divisor by which an exposure time is divided, and the exposure time is a time for which an image sensor is exposed to light that is imaged through a lens.