The present invention relates to a biological film-forming agent which is for facilitating wound healing and coating and protecting biological organs, and for coating and protecting damaged cells, wound surfaces, organs and damaged sites of organs, and wound surfaces reaching soft tissues such as muscle and facia, periosteum or bone cortex. Provided is a biological film-forming agent for suppressing exudation of intracellular fluid from damaged cells, suppressing expansion of inflammation reactions and secondary inflammation reactions resulting from production of fibrin and eliminating adverse effects caused by formation of stabilised fibrin on healing. Various problems can be solved by using the agent containing aluminium chloride, cyclodextrin and water as base components.