An inside door handle device comprising: a handle base suitable for being fixed to an inner panel that composes an inside of an automobile door; an opening portion formed of a through hole formed on one side of the handle base; a support beam that is formed in the opening portion; a pair of handle support portions in which one of the pair of handle support portions is provided on the support beam and the other of the pair of handle support portions is provided on the opening portion; a pair of lock knob support portions in which one of the pair of lock knob support portions is provided on the support beam and the other of the pair of lock knob support portions is provided on the opening portion; a handle body in which a grip portion located on a tip end side is urged and held onto the handle base while a base end side is being swingably supported on the opening portion with the pair of handle support portions interposed therebetween; and a lock knob that is arranged adjacent to the handle body, and has a base end side pivotably supported on the opening portion with the pair of lock knob support portions interposed therebetween, wherein one end of the support beam is protruded from an operation recessed portion side peripheral edge of the opening portion so as to go along a boundary portion between the handle body and the lock knob in the opening portion, and characterized in that the support beam has a fixed-fixed beam shape bent into a substantial L-shape; and the other end of the support beam is protruded from a peripheral edge of the opening portion, more on the operation recessed portion side than a tip end of a cover edge of the opening portion, in parallel to either of an axial direction of the pair of handle support portions or an axial direction of the pair of lock knob support portions in the opening portion. a handle base suitable for being fixed to an inner panel that composes an inside of an automobile door; an opening portion formed of a through hole formed on one side of the handle base; a support beam that is formed in the opening portion; a pair of handle support portions in which one of the pair of handle support portions is provided on the support beam and the other of the pair of handle support portions is provided on the opening portion; a pair of lock knob support portions in which one of the pair of lock knob support portions is provided on the support beam and the other of the pair of lock knob support portions is provided on the opening portion; a handle body in which a grip portion located on a tip end side is urged and held onto the handle base while a base end side is being swingably supported on the opening portion with the pair of handle support portions interposed therebetween; and a lock knob that is arranged adjacent to the handle body, and has a base end side pivotably supported on the opening portion with the pair of lock knob support portions interposed therebetween, wherein one end of the support beam is protruded from an operation recessed portion side peripheral edge of the opening portion so as to go along a boundary portion between the handle body and the lock knob in the opening portion, and characterized in that the support beam has a fixed-fixed beam shape bent into a substantial L-shape; and the other end of the support beam is protruded from a peripheral edge of the opening portion, more on the operation recessed portion side than a tip end of a cover edge of the opening portion, in parallel to either of an axial direction of the pair of handle support portions or an axial direction of the pair of lock knob support portions in the opening portion.