NOVELTY - Method for processing food using earthworm, involves providing box having surrounding wall and bottom wall in rectangle shape, where the bottom wall in the surface is inclined downgradient toward a one sidewall from an opposite to other sidewall, connecting one or more openings in the sidewall with the bottom surface of the wall that is installed along at least one side of agricultural field, and bedding earthworm bed in the box and spreading food on the earthworm bed, where the earthworm converts the food to compost by digesting the food.    USE - The method is useful for processing food which is useful as compost. The compost is useful in liquid fertilizer for agricultural field (claimed). The foodstuff is obtained from food industry and restaurant.    ADVANTAGE - The method is cost-effective, and produces fertilizer having high nutritional content.    DETAILED DESCRIPTION - Method for processing food using earthworm, involves (a) (i) providing box having surrounding wall and bottom wall in rectangle shape, where the bottom wall in the surface is inclined downgradient toward a one sidewall from an opposite other sidewall, (ii) connecting one or more openings in the box with the bottom surface of the wall that is installed along at least one side of agricultural field so that one sidewall may substantially face the side of an agricultural field, and (iii) bedding earthworm bed in the box and spreading food on the earthworm bed, where the earthworm converts the food to compost by digesting the food, (b) (i) providing box having surrounding wall and bottom wall in rectangle shape, where the bottom wall in the surface angular shaped inclined surface that inclines in downgradient toward a one sidewall and other sidewall in opposite portion, and (ii) performing the above-mentioned steps (ii) and step (iii) in (a), (c) performing the above-mentioned step (i) in (a), (ii) connecting one or more openings in the box with the branches or stem portion of single tree or trees in row, (iii) and performing the above-mentioned step (iii) in step (a), (d) (i) performing the above-mentioned step (i) in (b), (ii) substantially connecting the box with rows in trees or stems on one side wall and other side wall from the multiple trees in single row or different rows connected to a bottom wall surface, and performing the above-mentioned step (iii) in step (a), or (e) (i) base paper-like surrounding wall and bottom wall of center angle and bottom wall in the inclined surface which inclines in downgradient toward an inner peripheral wall from an opposite arc-shaped outer peripheral wall, (ii) connecting two or more unit boxes formed in the lower end portion of an inner peripheral wall to bottom wall surface that are installed in the circumference, where inner periphery wall may make branch spreading of trees a diameter and may face substantially the right circular tube surface center of stem, and (iii) performing the above-mentioned step (iii) in (a).