A railcar door apparatus (10, 110, 210, 310, 410, 510, 610) comprising: a side sliding door configured to open and close a door opening portion of a side bodyshell of a railcar; a first elastic member (21, 121, 221, 321, 421, 521, 621) attached to a door end of the side sliding door in a vertical direction; and a second elastic member (22, 122, 222, 322, 422, 522, 622) opposed to the first elastic member (21, 121, 221, 321, 421, 521, 621), wherein: the first elastic member (21, 121, 221, 321, 421, 521, 621) includes a first base portion and a first projecting wall portion projecting from the first base portion toward the second elastic member (22, 122, 222, 322, 422, 522, 622); the second elastic member (22, 122, 222, 322, 422, 522, 622) includes a second base portion and a second projecting wall portion (26, 27) projecting from the second base portion toward the first elastic member (21, 121, 221, 321, 421, 521, 621); when the side sliding door is completely closed, the first projecting wall portion and the second projecting wall portion (26, 27) are located so as to overlap each other when viewed from a normal direction of the side sliding door; characterized in that: when the side sliding door is completely closed, the second elastic member (22, 122, 222, 322, 422, 522, 622) does not contact the first elastic member (21, 121, 221, 321, 421, 521, 621) and a gap space is formed between the first elastic member (21, 121, 221, 321, 421, 521, 621) and the second elastic member (22, 122, 222, 322, 422, 522, 622); a plurality of grooves (25c, 25d, 26c, 26d, 27c, 27d) or projections extending in the vertical direction are formed on an outer surface of at least one of the first projecting wall portion and the second projecting wall portion (26, 27), the outer surface facing the gap space; and when the side sliding door is completely closed, the grooves (25c, 25d, 26c, 26d, 27c, 27d) or projections do not contact the first projecting wall portion or the second projecting wall portion (26, 27). a side sliding door configured to open and close a door opening portion of a side bodyshell of a railcar; a first elastic member (21, 121, 221, 321, 421, 521, 621) attached to a door end of the side sliding door in a vertical direction; and a second elastic member (22, 122, 222, 322, 422, 522, 622) opposed to the first elastic member (21, 121, 221, 321, 421, 521, 621), wherein: the first elastic member (21, 121, 221, 321, 421, 521, 621) includes a first base portion and a first projecting wall portion projecting from the first base portion toward the second elastic member (22, 122, 222, 322, 422, 522, 622); the second elastic member (22, 122, 222, 322, 422, 522, 622) includes a second base portion and a second projecting wall portion (26, 27) projecting from the second base portion toward the first elastic member (21, 121, 221, 321, 421, 521, 621); when the side sliding door is completely closed, the first projecting wall portion and the second projecting wall portion (26, 27) are located so as to overlap each other when viewed from a normal direction of the side sliding door; the first elastic member (21, 121, 221, 321, 421, 521, 621) includes a first base portion and a first projecting wall portion projecting from the first base portion toward the second elastic member (22, 122, 222, 322, 422, 522, 622); the second elastic member (22, 122, 222, 322, 422, 522, 622) includes a second base portion and a second projecting wall portion (26, 27) projecting from the second base portion toward the first elastic member (21, 121, 221, 321, 421, 521, 621); when the side sliding door is completely closed, the first projecting wall portion and the second projecting wall portion (26, 27) are located so as to overlap each other when viewed from a normal direction of the side sliding door; characterized in that: when the side sliding door is completely closed, the second elastic member (22, 122, 222, 322, 422, 522, 622) does not contact the first elastic member (21, 121, 221, 321, 421, 521, 621) and a gap space is formed between the first elastic member (21, 121, 221, 321, 421, 521, 621) and the second elastic member (22, 122, 222, 322, 422, 522, 622); a plurality of grooves (25c, 25d, 26c, 26d, 27c, 27d) or projections extending in the vertical direction are formed on an outer surface of at least one of the first projecting wall portion and the second projecting wall portion (26, 27), the outer surface facing the gap space; and when the side sliding door is completely closed, the grooves (25c, 25d, 26c, 26d, 27c, 27d) or projections do not contact the first projecting wall portion or the second projecting wall portion (26, 27). when the side sliding door is completely closed, the second elastic member (22, 122, 222, 322, 422, 522, 622) does not contact the first elastic member (21, 121, 221, 321, 421, 521, 621) and a gap space is formed between the first elastic member (21, 121, 221, 321, 421, 521, 621) and the second elastic member (22, 122, 222, 322, 422, 522, 622); a plurality of grooves (25c, 25d, 26c, 26d, 27c, 27d) or projections extending in the vertical direction are formed on an outer surface of at least one of the first projecting wall portion and the second projecting wall portion (26, 27), the outer surface facing the gap space; and when the side sliding door is completely closed, the grooves (25c, 25d, 26c, 26d, 27c, 27d) or projections do not contact the first projecting wall portion or the second projecting wall portion (26, 27).