The invention relates to the field of preliminary machining of laver, in particular to an anti-blocking cutter holder for detecting foreign matter of fresh laver. According to the cutter holder, a segment of widened concave hole is additionally formed in the tail end of an upper grate groove of the body of the cutter holder and used for buffering or releasing concentration and pressure of foreign matter in the process when the foreign matter in the laver is detected, concentration and accumulation of the foreign matter are remarkably improved, the frequency of the time period that the grate groove is blocked by the foreign matter is reduced, and meanwhile the foreign matter can be cleaned conveniently.