To provide a three-layer type key center applicable to various types of keys and achieving the effect of perfect theft prevention.

The key center consists of a key case 1, a limiter 2, a plurality of key plates 3 and a rotary barrel 4. The limiter 2 has a round plate body or oval plate as its rear step, penetrates the key case 1 and keeps a plurality of key plates 3 in the store space of the limiter 2. The limit plates of the limiter 2 enclose the plural key plates 3 from their both sides, and the rotary barrel 4 penetrates the plural frame-shaped plates 3. After an elastic unit is formed, it is made into contact with the bottom side of the rotary barrel to form a concealed-type double-latch key center. When the key is inserted into the rotary barrel 4, it rotates and moves a key ball layer, separates the corresponding key ball from the case, then turns and opens the key, and floats and moves the key ball along the axis Y.