Spindle and kinetochore-associated protein 1 (SKA1) is a microtubule-binding subcomplex of the outer kinetochore that is essential for proper chromosome segregation. SKA1 is required for timely anaphase onset during mitosis, when chromosomes undergo bipolar attachment on spindle microtubules leading to silencing of the spindle checkpoint. Recently, SKA1 has been highlighted as a biomarker in some types of cancers, however, the precise role of SKA1 in gastric cancer remains unknown. In order to investigate the role of SKA1 in gastric cancer, the expression levels of SKA1 were analyzed in 56 gastric cancer samples and 54 non-neoplastic samples by immunohistochemistry, and we found SKA1 was significantly overexpressed in gastric cancer tissues. Moreover, we employed lentivirus-mediated short hairpin RNA to knockdown SKA1 in the human gastric cancer cell line MGC80-3. Functional analysis indicated that SKA1 silencing significantly inhibited cell proliferation and colony formation, as determined by MTT and colony formation assays. The depletion of SKA1 in MGC80-3 cells also led to S phase cell cycle arrest. These results suggest that SKA1 could be used for gastric cancer early diagnosis as a biomarker. It is possible to enable a potential therapy based on targeting SKA1.