To obtain an easily macerating, moisture-proof paper, recoverable and recyclable as used paper, and useful as moisture-proof packaging paper for industrial products or the like, by heating and curing specific moisture-proof paper at specific temperature or higher.

This moisture-proof paper is by heating and curing, at 30°C or higher, moisture-proof paper whose support is coated, at least on one side, with a moisture-proof layer comprising a phyllosilicate compound treated with a coupling agent and a synthetic resin, e.g. styrene-butadiene polymer. Preferably, the moisture-proof layer contains a moisture-proofness improver comprising at least one type of compound selected from the group consisting of crosslinkable, polyvalent metallic compounds, and compounds respectively having methylol, aldehyde, epoxy, amine and amide groups.