Objectives of the invention are to maintain good maintainability, and to make a device further small and integrated. The invention provides an apparatus for controlling fluid supply. The apparatus comprises a flow path block, and a plurality of modules. The plurality of modules comprise at least a dismounting module which can be dismounted relative to the flow path block, and the dismounting modules are configured in a general line along a preset arrangement direction. A connecting flow path and a pair of inner thread portions are formed in the flow path block. The pair of inner thread portions are configured to be able to install the dismounting modules in any dismounting methods. The connecting flow path is connected between different modules. The connecting flow path and the inner thread portions are configured along a flowing direction of liquid in the flow path block, that is, the connecting flow path and the inner thread portions are generally configured in a line along the arrangement direction.