The present invention provides a retroviral vector containing a membrane protein having a hemagglutinin activity. The present inventors constructed a retroviral vector pseudotyped by the membrane protein having a hemagglutinin activity. This viral vector showed gene transfer at a high efficiency into host cells. In particular, it was established that genes can be transferred thereby at a high efficiency into cells into which genes can hardly be transferred by the conventional techniques, for example, blood cells and hematopoietic cells including hematopoietic stem cells, and mucous cells including mucosa epithelial cells. The viral vector of the present invention is highly useful as a vector for gene therapy.