We present tapered-slit filter devices for high-throughput viable circulating tumor cell (CTC) isolation and release. The membrane filter having an array of tapered-slits reduces the cell stress concentration at the edge of slit entrance, thus achieving viable CTC isolation with minimal stress. We fabricated the tapered-slit membrane from the UV exposure of spin-coated SU8 layers. The membrane filter device captures 82.44% of the cancer cells spiked in blood with the cell viability of 72.33% after 5 day culture of the captured cells; thus, allowing further molecular analysis and stable characterization of CTC for cancer diagnosis and prognosis.