Kwon Jeong-ja told the Associated Press news agency: "I'm 71-years old. How can I go for the rest of my life without this money?
"The money I invested was all I had for my future life."
Earlier this week, South Korea's bank regulator said Woori had failed to adequately explain the risks to its customers.
In a ruling on Tuesday the Financial Supervisory Service (FSS) said Woori would have to cover half the losses suffered by investors who had put money into the fund.
In a statement the FSS said the bank "did not provide explanatory notes to the investor, who had no experience with buying funds, when it sold the derivatives investment product".
The regulator added: "It also told the investor that the fund had almost a zero chance of losing the principal sum, leading the buyer to mistake it for a bank deposit in which the principal payment was guaranteed."