The present invention relates to a substance specific to human PD-1 comprising a part that recognizes human PD-1, a part that recognizes a membrane protein in cell membrane of human PD-1-expressing cells, and linkers. Since the substance specific to human PD-1 selectively can recognize human PD-1 and a membrane protein on cell membrane of human PD-1-expressing cells and can transmit inhibitory signal of human PD-1, it is useful for therapy and/or prevention of diseases caused by immunopathy.