To ensure high accuracy and stable temperature control and cost reduction.

This is a module block, comprising a piping joint 1 for mutually connecting functional parts, base blocks 11, 21, 31 for holding the joint 1, and a base plate 41 fixing the joint 1 and the base blocks 11, 21, 31 by sandwitching them with the functional parts. A gas flow inlet 3 of the joint 1 held by the blocks 21, 31 is arranged at a position of an outlet port of functional parts and the joint 1 and the base blocks 21, 31 are sandwitched between the base plate 41 and the functional parts and fixed to thereby form a gas flow passage. After a heater insertion hole 45 is provided to heat and keep the temperature of luid flowing in the gas flow passage, a heater is inserted therein, and a bottom of the joint 1 brought into contact with the base plate 41 is heated.