A seal structure (1) is a seal structure of a cooler apparatus (2) configured to: cause cooling unit trains (13) to move to convey cement clinkers placed on the cooling unit trains (13), the cooling unit trains (13) being arranged in an orthogonal direction such that side walls (21a and 21b) of the adjacent cooling unit trains are opposed to each other; and supply a cooling fluid to the cement clinkers from under the cooling unit trains (13). The seal structure (1) includes a cover body (31) and a sealing member (32). The cover body (31) is attached to a left side wall (21a) of one of the adjacent cooling unit trains and surrounds an upper surface and both side surfaces of a right side wall (21b) of the other cooling unit train (13), opposed to the left side wall (21a), to cover a gap (29) between the two side walls (21a and 21b). A labyrinth (36) communicating with the gap (29) and a dead layer (40) side is formed between the cover body (31) and the right side wall (21b). The sealing member (32) is provided at the labyrinth (36) so as to seal a gap between the cover body (31) and the right side wall (21 b).