PROBLEM TO BE SOLVED: To provide a seaweed bed creating apparatus capable of growing seaweeds suitable for natural environmental characteristics of a sea zone where a seaweed bed is to be created, capable of being easily handled, and capable of expecting settlement of benthic organisms.SOLUTION: A growth base material 111 on which seaweeds SW grow is disposed on one surface of a base part 110 of a cartridge 103. A cartridge receptacle 102 includes a table part and a holder part 105. The table part is set on the outer surface of a block disposed on the bottom of the sea BS, and a space SP is formed for benthic organisms to live. The holder part 105 is disposed on a first surface 107a side of the table part. The holder part 105 has an introduction part 115 for sliding and introducing the cartridge receptacle 102. The holder part 105 slidably holds an edge area 114 of the base part 110 of the cartridge 103 which is introduced from the introduction part 115 with the growth base material 111 turned in the direction of separating from the table part and which is made to fall by its own weight.
