Mosirites is a genus of anisoceratid ammonite from Hobetsu in Hokkaido; North Japan.

The type species is Mosirites mirabilis, known from multiple partial and complete specimens.

The holotype, HMG-2412 has a maximum diameter of 325 mm (12.8 in), and consists of a phragmocone and a part of the body chamber with length of about 150°.

[1] The generic name, Mosirites, is derived from the Ainu word for peaceful land or Hokkaido, and the suffix "-ites" which is common in ammonite genera.

The second species' specific name, serpentiformis, derives from the Latin words 'serpens' and 'forma' and refers to its snake-like form.