PROBLEM TO BE SOLVED: To develop a dental pretreatment agent which does not cause too heavy discharge, and maintains high viscosity and suitable consistency also after discharging operation from the syringe, and has properties of not spreading by weight of the pretreatment agent itself.SOLUTION: The invention provides a dental pretreatment agent wherein fumed silica has a mean first particle diameter of 5-100 nm, and satisfies the agglomerated secondary particle properties of the following i)-iii) measured by laser diffraction scattering method to disperse: i) a volume mean particle diameter of an aggregation secondary particle is 5-50 &mum ii) a volume% of the aggregation secondary particle with a volume particle diameter of 1 &mum or less is 20% or less and iii) a volume% of the aggregation secondary particle with a volume particle diameter of 100 &mum or more is 5% or less.
