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° 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.