<p>A process for waterglass production characterized in that a sodium-based by-product which has been yielded as a by-product in a process for improving the purity of silicon and which contains silicon and includes sodium silicate as a main component is dissolved in water to produce crude waterglass and to simultaneously dissolve the silicon and generate hydrogen gas, and thereafter the crude waterglass is filtered to produce waterglass. When a sodium-based by-product which has been yielded as a by-product in a process for improving the purity of silicon and which contains silicon and includes sodium silicate as a main component is to be utilized as waterglass, there has been a problem concerning hydrogen gas generation due to the silicon contained in the by-product. The process for waterglass production eliminates this problem and enables a safe and stable operation. The waterglass produced can be effectively utilized as transparent waterglass.</p>
