A voltage-pulse converting circuit according to an embodiment of the invention includes: a first input terminal and a second input terminal applied with an input voltage to be converted into a pulse; an integrator having positive and negative input terminals; an input switching unit switching connection between the first and second input terminal and the positive and negative input terminals of the integrator; and a first comparator comparing a first detection voltage with an output voltage of the integrator and a second comparator comparing a second detection voltage different from the first detection voltage with the output voltage, the input switching unit switching the connection based on a comparison result of the first and second comparators.