To provide a sub-chamber type gas engine for obtaining an effect of suppressing supercooling of a sub-chamber to promote combustion reaction and an effect of suppressing temperature rise of a sub-chamber member and an ignition plug during engine high load or the like to suppress their melting or the like.

The sub-chamber type gas engine has: a cylinder head 3 for being cooperated with a piston and a cylinder block to partition a main combustion chamber 10; a sub-chamber member 4 provided on the cylinder head 3 and forming the sub-chamber 11 in the inside; and the ignition plug 5 for igniting a fuel gas supplied to the sub-chamber 11. The sub-chamber member 4 includes: a nozzle hole 4a penetrating the main combustion chamber 10 from the sub-chamber 11; a first cooling liquid passage 4d partitioned around the sub-chamber 11; an attaching hole 4c1 for inserting the ignition plug 5; and a second cooling liquid passage 4e partitioned around the attaching hole 4c1. The sub-chamber type gas engine includes a first valve 4j for regulating a flow rate of a cooling liquid supplied to the first cooling liquid passage 4d and a second valve 4k for regulating a flow rate supplied to the second cooling liquid passage 4e.