Provided are a method and a device for maintaining the freshness of agricultural products, the method and device making it possible to reliably obtain a freshness-maintaining effect while efficiently using light energy by irradiating agricultural products with an appropriate amount of near-infrared light. Provided are: a method for maintaining the freshness of agricultural products, the method making it possible to reliably obtain a freshness-maintaining effect by irradiating harvested agricultural products with near-infrared light that includes a wavelength set within a wavelength region of 800-1000 nm so as to satisfy all of equations 1, 2, and 3, where X is the irradiance (W/m2) and Y is the irradiation time (sec)； and a device for maintaining freshness with which it is possible to implement the method. Equation 1: 413019X-1.872 ≥ Y ≥ 5966X-1.86 Equation 2: X ≥ 1 Equation 3: Y ≥ 0.01
