The present invention relates to a heat retaining agent for agricultural films comprising hydrotalcite-type particles which can satisfy all of a transparency required for heat retaining agents for agricultural films, dispersibility in resins, and handling property at a high level. According to the present invention, there are provided hydrotalcite-type particles having an oil absorption of not more than 35 mL/100 g and a ratio of an oil absorption to a plate surface diameter (oil absorption/plate surface diameter) of 140 to 190; a heat retaining agent for agricultural films comprising the hydrotalcite-type particles; and an agricultural film comprising the heat retaining agent for agricultural films.