Provided is a time-of-flight mass spectrometer including: a loop-orbit defining electrode (21) including an outer electrode (211) and inner electrode (212) located on the outside and inside of a loop orbit, respectively; an ion inlet (22); an ion outlet (23) provided in either the outer or inner electrode; a loop-flight voltage applier (28) configured to apply loop-flight voltages to the outer and inner electrodes, respectively; a set of deflecting electrodes (24) facing each other across a section of an n-th loop orbit, where n is a predetermined number, the deflecting electrodes including a first portion (241) which faces the n-th loop orbit and a second portion (242) which includes other portions; and a voltage applier (29) configured to apply deflecting voltages to the first portion so as to reverse the drifting direction of the ions flying in the n-th loop orbit, and a voltage to the second portion so as to create the loop-flight electric field.