Secure sealing is vital for planar type SOFCs to avoid the performance degradation and achieve long-term stable operation. Here we focus on the sheet type glass sealing which is produced by tape-casting method. High wettability of the glass is essential to avoid the stress concentration because low wettability increases the contact angle of the glass and makes the notch at the edge of glass sealing interface. We have evaluated the effect of temperature rising rate on the wettability of the sealing glass and the edge shape of it using the visualization test system. High temperature rising rate led to small contact angle of the sealing glass in some cases and can mitigate the stress concentration.