Sintered specimen which used for a blade of diamond tool was manufactured in order to verify $CO_2$ laser weldability depend on sintered temperature. Five kind of specimen were prepared and the range of temperature is from $600^{circ}C$ to $1000^{circ}C$ at intervals of $100^{circ}C$. As a result of the sintered density test, the porosity rate appeared in the range of $2.1%{sim}21.4%$. After welding, the most segments had exceeds the minimum fracture stress (600MPa, The Standard Safety of Europe) at the welding strength test except on the sintered at $600^{circ}C$. In case of the sintered at $700^{circ}C$, even satisfied the safety allowable stress but cannot get the good quality for bead appearance because of humping defect. In the conclusion, we could know that it showed not only relatively soundness bead but also enough welding strength when the sintered blade of diamond tool is included less than 4% of porosity rate.