To cause a water drop that invades from a hinge in a casing of folding portable information equipment, to hardly enter the casing along a flexible substrate inside the hinge.

A display casing 1 and an operating casing 2 are connected so as to be foldable with a rotary axis as a center, and a hinge 3 is provided for housing in its hollow portion a flexible substrate 32 for electrically connecting internal circuits of both the casings 1, 2. On an outer surface of the operating casing 2 that faces a portion 311 of the hinge 3 molded integrally with the display casing 1, at a gap in between, an overlap portion 50 constituted of an arcuate curved surface is formed. In this overlap portion 50, a through-hole 52 communicated with the operating casing 2 and a water guide channel 53 communicated with the through-hole 52 are formed, and water drops entering the gap are made to flow into the through-hole 52 and are removed from the gap.