Virus-based sensors using M-13 bacteriophages are considered as potentially useful techniques to detect harmful chemicals, such as endocrine disrupting chemicals and antibiotics. Despite their great potential, chemical detection using this color sensor is dependent entirely on gas phase samples. Here, a simple and rapid colorimetric sensor was fabricated using a genetically engineered M-13 bacteriophage for liquid detection. The hierarchical nanostructure with structural color can detect the target material with great sensitivity and selectivity. Liquid detection using a M-13 bacteriophage-based colorimetric sensor was performed to verify selectivity and sensitivity of the color sensor upon exposure to a liquid sample. Trinitrotoluene (TNT) was detected in ethanol solutions at concentrations as low as 40 pM, and 400 μM of three kinds of nitro-aromatic compounds could be identified using the M-13 bacteriophage-based colorimetric sensor. The liquid sensing technique described in this study may lead to the production of a viral color sensor for practical applications.