The ferry disaster, that killed some 3-hundred people last month, hit consumer sentiment hard with fewer people feeling the urge to go shopping or eat out.
The somber mood since the sinking prompted organizers to call off major festivals as well.
The Bank of Korea said on Tuesday that the consumer sentiment index in May tumbled 3 points from April to 105.
The index is a barometer of consumers' overall economic outlook.
A reading above 100 means more consumers are optimistic about the future than those who are pessimistic.
But the May figure is the lowest since September last year when the U.S. Federal Reserve's decision to begin tapering its stimulus program sent jitters through emerging markets.
Reflecting the sedate and cautious mood, money spent on travel and entertainment plunged in May while medical spending edged up.
Readings on current living conditions and future spending also shed two points compared to a month earlier.
A separate survey conducted on small-and-mid sized businesses showed eight out of ten business owners said they had been affected by the dropping consumer sentiment.
They reported an average of 30 percent drop in revenues after the ferry disaster from the same period last year.
Song Ji-sun, Arirang News.