Significant glacier shrinkage has generally been observed among Nepal Himalayas in recent years. The shrinkage is probably accelerated in the 1990s among the small glaciers. Large debris-covered glaciers were also observed to shrink more significantly than expected before. In addition to the increasing observations, glacier fluctuation models which can account for the characteristics of glaciers in the Nepal Himalayas have gradually been developed, and numerical experiments with the models have been performed. New knowledges on the glacier shrinkage during about thirty years since the 1970s are introduced as reviews of both the observations and the numerical experiments.