The invention relates to a construction block (2) made of inert material, such as concrete, comprising two opposite main faces (4, 6), an upper face (8), a lower face (10), and two opposite lateral faces (12, 14), the upper and lower faces (8, 10) and the lateral faces (12, 14) having, respectively, complementary reliefs that are able to interlock when several of the blocks are juxtaposed. The relief of the upper face (8) comprises two tenons (16) extending in parallel and at a distance from the two main faces (4, 6), respectively, and the relief of the lower face (10) comprises two corresponding slots (16′) extending in parallel and at a distance from the two main faces (4, 6), respectively.