Abstract: The invention pertains to a device adapted to apply thermoplastic cement for assembling shoe vamp sides, comprising a pair of heater units leading to feet suitable to spread cement along the edges of a shoe insole and a pair of supporting arms for said heater units fixedly mounted with respect to each other and connected to each other at their free ends by means of a pin, operated by an actuator, which can be disposed at a predetermined height above the insole. Each of said heater units is provided with a slide bar disposed parallelly to the axis thereof, axially and slidably engaged within a slide hole obtained in a small block carried by said supporting arms.