The present invention provides a technique for producing a tea wherein water-insoluble components of tea leaves have been made soluble in water and the natural umami components inherent to tea leaves have been increased. It also provides a technique for manufacturing a tea-based alcoholic drink which has "tea leaf-origin aroma", "umami and body" and "mild alcoholic aftertaste" in a good balance. Tea leaves are processed with an extruder at a temperature of 80 to 150.degree. C. and under a pressure of 0.2 to 30 MPa for 5 to 600 sec while supplying 1 to 100 parts by weight, per 100 parts by weight of the tea leaves, of water or an aqueous sugar solution. Thus, a processed tea leaf product is stably produced while avoiding blowout from the outlet. A tea extracted from this processed tea leaf product shows a significantly improved taste compared with one extracted from unprocessed tea leaves. Further, a tea-based alcoholic drink having a significantly improved taste can be produced by extracting a starting material, wherein the weight ratio of the processed tea leaf product as described above:tea leaves (b) is 1:9 to 1:0, with a solvent containing 5 to 80% by weight of an alcohol to give a tea extract.