The “Lambdameter” detector was specially designed for the study of cumulative Λ0-hyperons in the region of fragmentation of a target nucleus at rest in hadron-nucleus interactions under various initial conditions (energy and species of primary particle, atomic number of the target nucleus, emission angle of a Λ0-particle). The detector is used to measure the spectra of Λ0-particles in the kinetic energy range T from 40 to 150 MeV with a ≈ 5 MeV resolution, a relative systematic error of dσdT within the experiment of ⩽ 5%, and an absolute systematic error of ⩽ 10%. It also makes it possible to determine production cross sections (yields) with the same accuracy and polarization with an accuracy of better than 4%. Cumulative lambdas were detected at an angle of 90° in the lab system in the first run of the ITEP accelerator.