The detection systems of biomaterials, for example, DNA and protein, which are important in genetic and allergy tests, or those of bacteria causing various disease, are essential tools in preventive healthcare, the food security, and the environment conservation. These ensure a sustainable cultural life for all human beings. In order to solve these problems, many researchers are trying hard from dawn to dusk for the development of efficient detection methods of targets whose sizes range from nanometers to micrometers. In this contribution, we provide a review of our recent achievements concerning (1) Self-assembling fabrication method of a high-density assembled structure of metallic nanoparticles exhibiting strong optical response due to the collective phenomena of internal electronic systems in a nano-space and a novel principle for the optical detection of biomaterials using such a structure; (2) Fabrication method of a conducting polymer film with bacterial surface structure-imprinted micro-spaces and the detection method of bacteria using its high specificity. We also discuss the prospects for developing label-free, rapid and highly-sensitive biosensors based on these detection principles and methods.