A hybrid construction machine includes: an electric storage device temperature adjustment circuit; an engine cooling circuit including a first coolant and switchable between a state the first coolant after cooling the engine is introduced into the electric storage device temperature adjustment circuit and a state stopping introduction of the first coolant into the electric storage device temperature adjustment circuit; an equipment cooling circuit that cools, with a second coolant, equipment needing cooling, and switchable between a state the second coolant is introduced into the electric storage device temperature adjustment circuit and a state stopping introduction of the second coolant into the electric storage device temperature adjustment circuit; and a controller controlling the engine cooling circuit, the equipment cooling circuit, and a lead-out switching valve such that the first coolant or second coolant selectively flows, according to whether the electric storage device needs to be warmed or cooled.