PURPOSE: To provide a hot melt adhesive composition indicating the presence or absence of moisture or changing the color in response to the presence of moisture by including respectively specified polymer, acidic compound and wetness indicator as essential components.

CONSTITUTION: This composition is formed of 20-70 wt.% (hereinafter referred to as %) of a polymer which is a mixture of about 28-100% of a water sensitive polymer consisting of vinylpyrrolidone homopolymer and/or vinylpyrrolidone/ vinyl acetate copolymer and a balance polymer consisting of one or more polymers selected from ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer, and polyamide; 25-60% of an acidic compound consisting of one or more free (un)saturated monobasic fatty acids with an acid value of 137 or more and/or one or more rosin acid with an acid value of 130 or more; 40% or less of a water soluble wax; 60% or less of glycerol monostearate; 55% or less of castor oil hydride; 15% or less of polyalkylene wax; 60% or less of a compatible plasticizer; and a wetness indicator (e.g.; bromophenol blue) having the property of reacting with moisture to change the color of the composition consisting of the above components of a quantity capable of visually judging the dry or wet degree of the composition.