A gas sensor comprising: a gas detecting element extending in an axial direction and including a detecting electrode provided on an outer surface of a leading end side of the gas detecting element, and a lead portion connecting to the detecting electrode and extending toward a rear end side of the gas detecting element; a cylindrical metal shell housing the gas detecting element such that the gas detecting element protrudes from a leading end side of the metal shell; a powder layer filling a gap between the gas detecting element and the metal shell and covering at least a portion of the lead portion; and an insulating layer provided between the powder layer and the lead portion. Also disclosed is a method for manufacturing the gas sensor which includes forming the insulating layer by at least: applying a glass paste; drying the glass paste; and heat-treating the glass paste.