A grip heater device which is attached on a handle bar of a straddle vehicle and is gripped by a rider, wherein the grip heater device includes a tubular grip which is fittable to a bar part (la) of the handle bar, wherein the grip includes a grip body which can be gripped by the rider's hand, and a grip base end part which is provided at a location that is inward of the grip body in a vehicle width direction and is adjacent to the grip body, wherein the grip base end part is integrated with the grip body and has a diameter larger than that of the grip body, the grip body containing a heater therein which generates heat by electric power supplied to the heater, and the grip base end part being provided with a temperature adjustment member, which is a single button, which is operated by the rider to adjust a temperature of the heater, wherein the electric power control section shifts levels of the amount of the electric power to be supplied to the heater, in a predetermined sequence, in a case where the temperature adjustment member is operated by the rider for a time shorter than a predetermined time, and wherein the electric power control section sets the amount of the electric power to be supplied to the heater to zero, in a case where the temperature adjustment member is operated by the rider for a time longer than the predetermined time, the grip heater device comprising: a display unit provided at the grip base end part and including a first light source and a second light source which are disposed adjacently to each other, the first light source and the second light source being configured to emit light in such a way that a color of the light emitted by the first light source is different from a color of the light emitted by the second light source; and a controller being connected to the grip and including an electric power control section which controls an amount of the electric power to be supplied to the heater in response to an operation of the temperature adjustment member, and a light source control section which controls the first light source and the second light source, wherein the controller is mounted on a vehicle body at a location that is distant from the grip, and electric power is supplied from a power supply mounted in the straddle vehicle to the grip and the controller via wires, wherein the display unit is configured to perform: a first color display in which the first light source blinks or is ON and the second light source is OFF to display a first color, a second color display in which the first light source is OFF and the second light source blinks or is ON to display a second color, and a third color display in which both of the first light source and the second light source blink or are ON to display a third color formed by mixing the first color and the second color, and wherein the light source control section causes the display unit to perform a temperature display with a blinking pattern corresponding to the amount of the electric power supplied to the heater, by use of one color display selected from the first color display, the second color display, and the third color display, in response to the operation of the temperature adjustment member.