The present invention is to provide a thermo-valve which can be operated with no unnecessary work to fill fluid easily and without fail into a circuit having the fluid flow therethrough at the time of a high temperature range. The thermo-valve comprises a valve housing 21, and a center guide shaft 27 movable to assume a valve movement limitation position GP1 in which a valve member 31 is retained to a second operation position BP2 to open a specific port, and a valve movement allowance position in which the valve member 31 is allowed to displace, the center guide shaft 27 and the valve housing 21 allowing a bimetal ring 51 to be disposed therebetween, and the bimetal ring being deformed to retain the center guide shaft 27 to the valve movement limitation position GP1 at the initial stage until the temperature of oil in the valve housing 21 firstly reaches the high temperature range, and to release the center guide shaft 27 from the valve movement limitation position GP1 when the temperature of the oil in the valve housing 21 reaches the high temperature range.