To examine the dynamics of species diversity during secondary succession, growth, death and recruitment of trees (diameter at breast height, dbh ≥ 4.5 cm) were monitored for 39 years (1966 to 2005) in two plots (P-1 and P-3, 40 m × 40 m each) in a Japanese warm-temperate secondary forest recovering from clearcutting that occurred in the 1910s. Typhoons in the early 1990s seriously damaged P-1 and moderately damaged P-3. During the 39 years, species diversity and evenness increased over time in both plots. We introduced new induces to separately examine effects of recruitment and mortality on species diversity and found that recruitment always contributed to increases in species diversity but mortality did not. Recruitment increased species diversity because the recruitment rate of rare species was higher than that of abundant species. This reflected delayed recruitment of late successional species before the typhoons and the mass recruitment of early successional species after the typhoons. Through these processes, the typhoons enhanced species diversity in this Japanese warm-temperate forest.