MicroRNAs are crucial tumor regulators to tumor development and progression. MiR-30c-2-3p can suppress malignant progression of tumor cells, but no study has reported the modulatory process of miR-30c-2-3p in gastric adenocarcinoma (GA). We herein investigated role of miR-30c-2-3p in GA cells. Here, we evaluated gene level in cancer cells by qRT-PCR. CCK-8, colony formation, flow cytometry, and transwell assays revealed biological functions of miR-30c-2-3p and ARHGAP11A. Genes downstream of miR-30c-2-3p were acquired through bioinformatics analysis. Our results suggested a low level of miR-30c-2-3p in GA tissue and cells, while its high expression could repress the malignant progression and promote cell cycle arrest and apoptosis of GA cells. Besides, ARHGAP11A was downstream of miR-30c-2-3p, with up-regulated ARHGAP11A facilitating malignant progression and repressing cell cycle arrest and apoptosis of GA cells. In addition, changes in GA cell functions caused by high ARHGAP11A expression could be partially offset by enhancing miR-30c-2-3p. Thus, our observations indicated that miR-30c-2-3p was a tumor repressor that could inhibit GA progression via modulating ARHGAP11A.