An apparatus for producing a plate glass which comprises(A) a melter for storing a molten glass material,(B) a molding portion for molding the molten glass material from the melter into a plate,(C) a temperature adjusting tank located between the melter and the molding portion for maintaining the molten glass material from the melter at a uniform temperature, said temperature adjusting tank having a glass material channel for introducing the molten glass material maintained at the uniform temperature into the molding portion in a position facing on the molding portion, and(D) a tweel for adjusting a flow rate of the glass material which is raisable and lowerable in the glass material channel and has a hole through which a surface layer stream of the molten glass material can be separated and passed in the glass material channel.