A mast cell surface antigen, DNA thereof and an antibody against the antigen are provided. The amino acid sequence of this mast cell surface antigen is the translation of the coding region of its DNA. The base sequence of this DNA has been clarified in the following manner. Namely, mast cells obtained by incubating cord blood monocular cells are co-incubated with primary culture of fibroblasts to give connective tissue type mast cells (MC-TC). Then mRNA is extracted from this MC-TC cell extraction and a cDNA library is constructed therefrom. Immunological screening is carried out with the use of anti-MC-TC antiserum and the base sequence of the positive clone thus obtained is identified. Owing to the clarification of the amino acid sequence of this mast cell antigen, it becomes possible to reveal the role of mast cells in the pathology of allergic diseases and thus an antibody against mast cells can be easily obtained.