PROBLEM TO BE SOLVED: To provide a hothouse and a heat-retention cover which have both light-use properties and heat-retaining properties.SOLUTION: A film contains, based on synthetic resin 100 pts.wt., a hydrotalcite compound 1-20 pts.wt., the hydrotalcite compound represented by general formula (1): MgAl(OH)(CO)/mHO (where X is in the range of 4.0<；X&le；6.5 and m represents 0 or a positive number), the hydrotalcite compound in which a molar ratio Robtained by 2&thetas； of a (110) face based on the X-ray diffraction method and a molar ratio Robtained by chemical analysis satisfy R-R&le；0.7, and the use of such a film allows a hothouse or a heat-retention cover to have both transparency and heat retaining properties.【課題】光の利用性と保温性を兼備した温室および保温カバーを提供する。【解決手段】合成樹脂１００重量部に対し、下記一般式（１）で表され、ＭｇＸＡｌ２（ＯＨ）２Ｘ＋４（ＣＯ３）・ｍＨ２Ｏ （１）（上記式のＸは４．０＜Ｘ≦６．５の範囲にあり、ｍは０または正数を表す。）Ｘ線回折法による（１１０）面の２θより求められるモル比Ｒ１と化学分析より求められるモル比Ｒ２が｜Ｒ１－Ｒ２｜≦０．７を満たすハイドロタルサイト類化合物１～２０重量部を含有させたフィルムを用いることにより温室または保温カバーに透明性と保温性を兼備させる。【選択図】なし
