To easily pull up an anchor even when sea weed and the like wind around anchor claws.

This anchor has an anchor shank 1, an anchor head 3 rotatably attached to the anchor shank 1, and a rotational angle regulation member 7 which regulates the rotational angle of the anchor head 3 in respect to the anchor shank 1, and releases the regulation of the rotational angle of the anchor head 3 when force larger than the specified one is applied to the anchor head 3. The rotational angle regulation member 7 is composed of a bar-like member which is fixed to the anchor head 3 at its bilateral ends and arranged in a cutout 1a formed on a lower end of the anchor shank 1 at its intermediate portion. Regulation of the rotational angle can be released by breaking the rotational angle regulation member 7.