Abstract: The present invention provides a defoaming agent composition in gel form, of number 1 NLGI grade or harder, for application to the inside wall of a container, being a composition for defoaming bubbles generated from lubricating oil present within a container. The present invention further provides a method of defoaming lubricating oil characterised in that it includes a step of applying a defoaming agent composition in gel form, of number 1 NLGI grade or harder, to the inside wall of a container for lubricating oil and characterised in that this step is a step in which said defoaming agent composition is applied to the inside wall face at or above the oil surface of the lubricating oil, or higher than this.