Single-carrier (SC) space-time block coded (STBC) time-division duplex (TDD) transmission achieves a good bit-error rate (BER) performance while the channel state information (CSI) is not required at the mobile terminal (MT). However, in a high mobility environment, the channel changes within a STBC codeword and the BER performance significantly degrades due to the interference caused by the orthogonality distortion of STBC codeword. In this paper, we propose a multi-block (MB)-frequency-domain equalization (FDE) for SC-STBC-TDD transmission in a high mobility environment. The STBC codeword consists of multiple signal blocks. The proposed MB-FDE uses jointly optimized multiple FDE weight matrices, each associated with each signal block in a STBC codeword. We evaluate, by computer simulation, the BER performance when using the proposed transmit/receive MB-FDE and show that the proposed MB-FDE achieves a good BER performance in a high mobility environment.