To provide a fluid control device which can be easily dismantled and assembled, and in which the deterioration of seal performance due to distortion is prevented.

An upper connection layer 4 and a lower connection layer 5 are provided for achieving serial connection and parallel connection between fluid control devices. The upper connection layer 4 comprises parallel arrangement of vertically disposed block type couplers 41, 42, 43, and 44 each having a vertical passage 61 for connecting a line of mutually adjacent fluid control devices to each other, and a through passage 62 connected to the fluid control devices. The lower connection layer 5 comprises block type couplers 56, 57, and 58 each having a lateral communication passage 64 for connecting the through passages 62 of the couplers 41, 42, 43, and 44 in the upper connection layer 4 which are laterally disposed, and plural block type couplers 51 for communicating the through passages 62 in the couplers 41, 43, and 44 in the upper connection layer 4 with inlet/outlet side couplers 52 and 53. The couplers 51, 56, 57, and 58 in the lower connection layer 5 are attached to a base plate 2 by screws from above, and the couplers 41, 42, 43, and 44 in the upper connection layer 4 are attached to the couplers 51, 56, 57, and 58 in the lower connection layer 5 by screws from above.