The 2016 Meinong, Taiwan, earthquake ( 6.4) occurred in the district of Meinong of the city of Kaohsiung, southern Taiwan, on 6 February 2016, and caused severe building damage in the Tainan area (downtown Tainan and the neighboring districts of the city of Tainan). Large long‐period velocity pulses in both the east–west (E‐W) and north–south (N‐S) components were recorded by several strong‐motion stations deployed in the Tainan area. To investigate source effects as reasons for the characteristics of the recorded velocity pulses, we modeled the earthquake source fault and performed a joint source inversion of the waveform and geodetic datasets. The results show that the main rupture, which consisted of strike slips and low‐angle dip slips, propagated from the hypocenter toward the west‐northwest (WNW) nearly along the fault strike. The area of this main rupture was located west of the hypocenter and close to the Tainan area. Aided by theoretical calculations, we confirm that these rupture processes and positional relationships of the earthquake caused the rupture directivity effect on the strong ground motions in the Tainan area, generating large long‐period velocity pulses in the two horizontal components.