We examined the data of 24 patients with Henoch-Schönlein purpura nephritis (HSPN) over a 5-year follow-up period. Proteinuria, sediment RBC and CRP significantly decreased between the time of diagnosis and the end of the 5-year period. In the steroid usage group (n = 16), proteinuria was significantly higher, and crescent formation was significant higher at the time of diagnosis than in the non-steroid usage group (n = 8). However, there was no significant difference in the decrease in eGFR from the baseline at the end of the 5-year period between the two groups. Furthermore, to clarify the factors influencing the risk of renal function deterioration, we divided the patients into two groups, the (delta eGFR/pre eGFR) <0.25 group (n = 13) and (delta eGFR/pre eGFR) >0.25 group (n = 11), and compared the clinico-pathophysiological characteristics between the two groups. In the (delta eGFR/pre eGFR) >0.25 group, the ratio of glomerular obsolescence at the time of diagnosis was significantly higher than in the (delta eGFR/pre eGFR) <0.25 group. Glomerular obsolescence was identified as an independent risk factor for renal function deterioration. In this study, the prognosis of HSPN was related to glomerular obsolescence rather than to the disease activity. It may be necessary to consider the decrease in nephrons, in accordance with non-immunological glomerular obsolescence, in addition to immunological treatment to clarify the prognosis.