To detect the temperature state of a storing place regardless of the setting attitude at a low cost by filling a transparent thick-wall vessel closed by a synthetic resin thin lid with water, and fitting the lid side of the thick-wall vessel to a bottomed vessel.

A transparent synthetic resin upper vessel 1 is filled with water 4 of about 4, a synthetic resin thin lid 2 is put thereon so as not to leave the air in the inner part to seal the water 4, and the opening side of the upper vessel 1 is press-fitted to the opening part 12 of a lower vessel 3. When the environmental temperature of a product to be stored gets close to 0°C, the water 4 in the upper vessel 1 is expanded, and the upper vessel 1 is contracted as the environmental temperature lowers. The water 4 in the upper vessel 1 is compressed by the two actions of expansion and contraction, a thin membrane 10 is broken when it can not resist to the hydraulic pressure, and the water 4 in the upper vessel 1 runs into the lower vessel 3. When the thickness of the thin film 10 is set so as to be broken at the lower limit temperature of the environment for storing the product, the temperature state of the storing place can be detected by the breakage of the thin film 10.