A hydrogen flame ionization detector includes a nozzle configured to eject a sample gas upward, a cylindrical collector provided above the nozzle with a longitudinal direction thereof vertically oriented, the collector being configured to collect ions generated by a hydrogen flame formed at a tip of the nozzle, an insulator provided to hold the collector therein in such a manner as to extend in a radially inward direction of the collector, and a collector housing configured to accommodate the collector therein in such a manner as to surround an outer peripheral surface of the collector while holding a peripheral portion of the insulator. An accumulation suppression structure is provided above the insulator to suppress a material emitted from an upper end of the collector from being accumulated in such a manner as to shorten an insulation distance between the collector and the collector housing.