To provide a trochoid pump capable of preventing the reduction of pump efficiency while suppressing the occurrence of a vapor lock phenomenon based on the rise of fuel temperature.

This trochoid pump is constituted such that a deaeration hole H communicated with the outside is formed on a bottom face 10e of a rotor casing groove storing a trochoid gear T, and the deaeration hole H is positioned and formed in a section blocked by any fringe part on the front side in the direction of rotation of inner and outer teeth 12a, 13a of inner rotor 12 and an outer rotor 13 on the tip side in the direction of rotation constituting an arbitrary pump chamber PR formed in the trocoid gear T and having the maximum volume to discharge vaporized fuel as the arbitrary pump chamber PR reduces its volume.