The 34-year-old will see his current deal with the Bundesliga champions expire next summer, and he is supposedly a target for Chelsea.
However, Bayern are said to be reluctant to offer Neuer a five-year deal due to his age, and Matthaus believes that the goalkeeper is edging towards a departure from the Allianz Arena.
Speaking to Sky Germany, Matthaus said: "I can understand his desire for security and a long contract very well. But five years is also a long time.
"He should, as mentioned, not forget how loyal FC Bayern was to him in every phase. For both sides, it would be wonderful if Manuel stays a few years more.
"He should first extend for three years and if he's still healthy and performs he'll get the next contract. I think the signs are pointing to his departure.He wants to play. He wants to play more often and longer. In light of his quality, that's understandable.
"Probably a little more was expected of him, and the expectations he put on himself were undoubtedly higher. I don't think that he will still be playing in Munich next season."
Neuer has won seven Bundesliga titles and one Champions League during his nine-year stint at Bayern. body check tags ::