Hsinchu, Taiwan, January 9, 2006 - UMC (NYSE: UMC, TSE: 2303) today released an important announcement:

1. On the afternoon of January 9, 2006, the Hsinchu District Prosecutor's Office announced its decision to indict former UMC Chairman Bob Tsao and former UMC Vice Chairman John Hsuan.
2. On the morning of January 9th, Bob Tsao and John Hsuan officially retired from their positions on the UMC Board. At the same meeting, the Board elected CEO Dr. Jackson Hu to the position of Chairman of UMC, in addition to his current role as CEO. Consequently, the indictment should not in any way affect the future operations of the company.
3. UMC believes that the indictment of Bob Tsao and John Hsuan is of a purely political nature and caused by the special nature of the relationship between Taiwan and Mainland China. These indictments in no way reflect on the honesty and integrity of Mr. Tsao or Mr. Hsuan.
4. Both Bob Tsao and John Hsuan have chosen to forsake their personal interests in order to protect the equity of UMC's shareholders and to prevent injury to the company. Their decision is characteristic of their selfless commitment to the company and is worthy of praise.

UMC (NYSE: UMC, TSE: 2303) is a leading global semiconductor foundry that manufactures advanced process ICs for applications spanning every major sector of the semiconductor industry. UMC delivers cutting-edge foundry technologies that enable sophisticated system-on-chip (SoC) designs, including volume production 90nm, industry-leading 65nm, and mixed signal/RFCMOS. UMC's 10 wafer manufacturing facilities include two advanced 300mm fabs; Fab 12A in Taiwan and Singapore-based Fab 12i are both in volume production for a variety of customer products. The company employs approximately 12,000 people worldwide and has offices in Taiwan, Japan, Singapore, Europe, and the United States. UMC can be found on the web at http://www.umc.com.