It is intended to provide novel biobeads characterized by having a foreign genetic substance or a physiologically active substance which is immobilized to a calcium alginate microgel prepared by using sodium alginate having a low viscosity. It is also intended to provide a method of efficiently transferring the genetic substance or the physiologically active substance into cells using the biobeads. The above-described biobeads prepared by using sodium alginate having a low viscosity have a small particle size so that they would likely come into contact with cells at an elevated frequency. Using the biobeads, cells can be transformed at a high efficiency. These biobeads are applicable to the PEG method, which makes them useful in providing novel biobeads whereby a high transformation efficiency can be established.
