Provided is a high purity crystal form of 2 (3 5 dimethyl 1H pyrazol 1 yl) 5 methylphenol that is stable during storage industrial production and distribution. Also provided is a method for producing the crystal form. Provided are stable high purity crystals of 2 (3 5 dimethyl 1H pyrazol 1 yl) 5 methylphenol and a method for producing the crystals by using a boron compound.