[Problem] To provide a fluid control device which is further miniaturized and integrated without reducing the supply flow rate of a fluid. [Solution] This fluid control device comprises base blocks 10B, 10C and fluid devices 120, 130 arranged on the upper surfaces of the base blocks 10B, 10C, respectively. The base blocks 10B, 10C each have projecting tube portions 10p2, 10p1 projecting in the longitudinal direction. The projecting tube portions 10p2, 10p1 each communicate with a corresponding second flow passage 13d. The projecting tube portion 10p2 on the downstream end surface of the base block 10B and the projecting tube portion 10p1 on the upstream end surface of the base block 10C are air-tightly and liquid-tightly connected to each other by a welding material WL.