Private spending has declined even among Koreans in their 20s, who have traditionally been the most avid consumers.
According to Hyundai Research Institute on Sunday, average monthly spending by people in their 20s fell from W1.7 million in 2007 to W1.5 million last year (US$1=W1,125).
Private spending in their 30s and over 60 also declined slightly, but it rose by W200,000 a head among people in their 40s and 50s.
Twenty-somethings are increasingly burdened by their rental payments, while those in their 30s have to service housing-related debts.
Over the same period, the average net monthly income of people in their 20s dwindled 15 percent from W2.7 million to W2.3 million, the only age group to see a decline.
People in their 30s up saw wages increase between W200,000 and W700,000 over the same period.