Previous studies have identified possible linkages between solar activity and tropical cyclone activity in the United States and Caribbean. This study used historical typhoon records dating back to the early 1700s, the Central Weather Bureau records (since 1897), and the JTWC (Joint Typhoon Warning Center) (since 1945) to investigate the relationship between solar activity and the number of typhoons in Taiwan. The results show that a negative relationship exists between solar activity and typhoon frequency in Taiwan at decadal time scales. Fewer typhoons occurred during the periods 1770 to 1790 and 1930 to 1960, with a higher number of typhoons occurring during 1810 to 1830 and 1870 to 1930. A likely mechanism for the relationship is that more intense solar activity can warm the lower stratosphere and the upper troposphere through absorption of solar radiation by atmospheric ozone. This would decrease the convective available potential energy and reduce the frequency of typhoon occurrence. As a consequence, fewer typhoons form over the western North Pacific with fewer affecting Taiwan. The negative correlation between solar activity and the number of typhoons affecting Taiwan is important to understand changes in the frequency and behavior of typhoons resulting from climate change.