PURPOSE: To obtain a processed aquatic product imparting an added value to loose herring roe and having a special texture and flavor having the appearance extremely resembling to MENTAIKO (ovarian cyst of walleye pollack) by charging a mixture of loose herring roe seasoned and colored in red and a viscous matter into the ovarian cyst (MENTAIKO).

CONSTITUTION: Loose herring roe 3 is subjected to seasoning and coloring in red with dipping into a seasoning solution 5 containing an edible reddish pigment. Viscous matter 4 (e.g. kelp-containing yam) is added to the resultant herring roe, and then mixed. Thus prepared mixture 2 is charged into ovarian cyst 1 (MENTAIKO) to form the objective processed aquatic product A. Suitable seasoning can be used for the seasoning solution, besides, e.g. bonito extract, MIRIN (SAKE from glutinous rice), glucitol, sorbite or mustard, etc.