An objective of the invention is to maintain good maintainability of a device and make the device more miniaturized or integrated. The structure of a flow path block is that a flow path of a fluid is formed in the block, and a plurality of fluid controllers are arranged on an arrangement direction, and the fluid controllers can be installed. In addition, the structure of the flow path block is that a group of a plurality of fluid control devices on an arrangement direction is arranged on a width direction and the fluid control devices can be installed. A first flow path as the above flow path is arranged along an arrangement direction, so that the plurality of fluid control devices form the above group are connected with each other. A second flow path of the above flow path is arranged along a width direction, so that each of the group is connected. The flow path block is characterized in that the flow path block has a connection portion. Under the condition that the two flow path blocks are arranged in parallel on a width direction in an adjacent manner, the connection portion can make the second flow paths of the two flow path blocks connected.