A reticulate heater has a net-mesh-like-structured heat generator 2 including a plurality of heater wires 20 each having the same wire diameter of from 0.02 to 0.12 mm. The plurality of heater wires 20 are formed into the net-mesh-like-structured heat generator 2 by a tricot knitting technique wherein loops are vertically formed by vertically knitting the heater wire on a continuous and planar basis. The knit meshes of the tricot knitting each have a pitch of 0.5 to 5 mm. Also, the heater wires may be the ones prepared by covering the heater bare wires with a for-enamel-wire coating. Further, the net-mesh-like-structured heat generator 2 may be the one including a plurality of first heater wires each consisting of a heater bare wire only and a plurality of second heater wires each prepared by covering the heater bare wire with a for-enamel-wire coating, the first and second heater wires being formed into the net-mesh-like-structured heat generator by a tricot knitting technique. As a result of this, the reticulate heater can be close adhered also to a complex curved surface. In addition, the reticulate heater can be also brought to a state of its being electrically very stable. Also, it can be arranged that a prescribed amount of heat generated be obtained.