Abstract: A cigarette lighter with a built-in battery checker for use in automobiles which comprises two parts, one being a heater part in which a movable body provided with a heater at the tip of a push nob is mounted slidably in reciprocal front and rear directions to a holder and the other being a basal part into which the heater part is detachably inserted in such manner that when the push nob is pushed to bring the heater into contact with an electrode plate connected to a battery, the heater can be heated by electric current sent from the battery so as to enable the heater part to be pulled out from the basal part, characterized in that the push nob is provided inside with a variable illumination means in which brightness of the illumination is diminished according to increase in the degree of consumption of the battery and a standard illumination means for comparison in brightness with the variable illumination means.