To provide a protective cover that can protect convex corners and concave corners of wiring and/or piping material without trouble even where the convex corners or concave corners of building walls are not exactly 90° crossings.

A protective cover comprises a base formed only of a first base plate part 1 fixed to a wall face W₁ out of two wall faces W₁ and W₂ crossing each other substantially orthogonally, with a pair of engaged concaves (engaged parts) 3 being provided on the first base plate part 1, and an L-shaped lid provided with a pair of engaging pieces (engaging parts) 23 engaging the pair of engaged concaves (engaged parts) 3. The lid, in a state of being engaged with the base, is configured to be slidable along the one wall face W₁.