[en] A high-beta plasma of β_t∼0.1 and εβ_p>2 is produced and its confinement properties are studied in a screw pinch of moderately elongated cross section. The initially constricted high-beta plasma column is surrounded by a force-free current layer and expands radially. The energy confinement time is much less than that from the empirical scaling of an ohmically heated tokamak, but it gradually improves as β_p decreases. The fast plasma-energy decay and the fast boundary diffusion are considered to be caused by the ballooning mode. (author)