A cell line of Accession No. NITE P-03458. A producing method of a cell line includes: a transfection step of transfecting a vector into a cell, where the vector includes a nucleic acid sequence encoding a nonstructural protein of a coronavirus, a reporter protein including a drug-resistant protein, and a structural protein of the coronavirus; and a selection step of performing selection on the cell obtained in the transfection step using a drug.