Micropatterns consisting of reduced graphene oxide (rGO) and graphene oxide (GO) were fabricated via laser direct writing where an insulating GO was converted to a conductive rGO by laser-induced reduction. The rGO/GO microinterdigitated electrode showed humidity sensing behaviors. The influence of the shape and size of the rGO/GO microinterdigitated electrode was studied to discuss the sensing mechanism and to improve the sensitivity. Three kinds of rGO(w)/GO(g) micropatterns were prepared by laser direct writing on a GO-coated PET (polyethylene terephthalate) substrate using a CW 405 nm semiconductor laser, where w and g are the rGO electrode width and the GO gap width between rGO electrodes in micrometer unit, respectively. The humidity sensing properties of rGO(400)/GO(100), rGO(160)/GO(40), and rGO(80)/GO(20) were studied by monitoring the output voltage waveform from an electronic circuit consisting an rGO/GO interdigitated electrode and resistors in AC mode operation. The sensitivity enhancement induced by charging property of an rGO/GO interdigitated electrodes was observed accompanying transient decay of the output voltage. The shape and size of an rGO/GO interdigitated electrode remarkably influenced the humidity sensing behaviors depending on the contribution ratio of C and R parameters.