The fracture toughness, $J_{IC}$ of high frequency electric resistance welded steel pipe for smooth and side-grooved CT specimen was evaluated by unloading compliance method. The crack growth, .${delta}a$ was obtained from the equation of Donald and Saxena & Hudak, and $J_{IC}$ was determined from the curve of J-${delta}a$</TEX;> relations. The crack growth on the experiment using unloading compliance method is underestimated as compared with ${delta}a$ measured directly by the SEM, so the reliability of $J_{IC}$ from saxena & Hudak equation is large than that from Donald. The $J_{IC}$ value of side-grooved CT Specimen is estimated less than that of smooth, and this is the effect of the side-groove, the shear-lip of crack tip and the reduction of crack tunnelling phenomena.