An electrode for a lithium secondary battery includes a thin film of an active material having a first phase that reacts with Li dominantly and a second phase that reacts less readily with Li than the first phase and exists at least before initial-cycle charging and after discharging in each cycle following the initial cycle. A surface of the current collector has an arithmetical mean roughness Ra of 0.1 .mu.m or greater. A surface of the thin film has irregularities formed corresponding to the irregularities of the current collector surface. By the charging and discharging in the initial cycle and thereafter, gaps form along the thin-film thickness on lines connecting valleys in the thin-film surface irregularities and valleys in the current-collector surface irregularities, and the thin film is divided into columnar or insular structures by the gaps.