A coupling solenoid valve, of which both side faces in the valve-width direction are coupling faces for coupling another solenoid valve, including a main valve unit for switching a fluid channel using a spool, and a solenoid operating unit for driving the spool, wherein a housing of the main valve unit is divided into plurality of blocks, a valve hole for accommodating the spool is formed in a center block, a bottom block is made up of a synthetic resin, plurality of coupling communication holes are formed in this bottom block, and also a connection tube is formed in an integrated manner.