WATERTIGHT PACKING

PROBLEM TO BE SOLVED: To provide a watertight packing formed in a simple configuration, capable of suppressing increase of the number of components to reduce cost.SOLUTION: A watertight packing P is used for a thermal insulation panel A in which a thermal insulation material 3 is filled between a front side skin 1 and a back side skin 2 to form a panel body 4, a fitting recess 7 is formed between a pair of recessed part side walls 7a provided at an upper end part of the panel body 4, and a fitting protrusion 8 is formed at a lower end part of the panel body 4. The watertight packing P comprises: a surface covering part P1 formed along the surface of the upper end part of the panel body 4; and a rear face covering part P3 extendedly provided above the surface covering part P1 and formed in a foldable manner so as to follow along the rear face of the recessed part side walls 7a, and is formed to have a substantially constant cross-sectional shape over the full length in the lengthwise direction.