Cooking by the same method often results in prepared foods differing in quality from person to person.We focused on the observation skill of professionals and non-professionals during hot-mixing with the same method. The relationship between the observation skill and quality evaluation of the prepared food was explained. The observation skill was compared by the authors scoring eye movement, the distance of eye movement being detected by image processing. The prepared food was then compared by measuring the physical properties of hardness, starch gelatinization, structure and sensory evaluation. We confirmed the effect of teaching the observation skill to non-professionals.The food prepared by professionals was better than that by non-professionals and had the preferred hardness. The degree of starch gelatinization was also higher and a different structure was apparent.The observation skill by the professionals was higher scoring than that by the non-professionals, and the distance of eye movement was longer. We confirmed that the quality of the prepared food was related to this observation skill. Moreover, the observation skill and quality evaluation of non-professionals was improved by teaching the observation skill of the professionals. We confirmed the effect of observation skill as one of the teaching methods for hot-mixing.