Glossiness inspection device, glossiness inspection method, and image forming apparatus

A glossiness inspection device comprising:

• an illumination device that emits irradiation light;
• a light receiving device that receives reflected light of the irradiation light reflected by a glossiness detection target and outputs a light reception detection signal according to an amount of the received light;
• a correction plate that includes at least a first gloss region having a first glossiness and a second gloss region having a second glossiness lower than the first glossiness;
• a dimmer that adjusts an amount of the irradiation light;
• a detection signal adjuster that adjusts a gain for amplifying the light reception detection signal;
• an irradiation position controller that selectively irradiates the first gloss region and the second gloss region with the irradiation light;
• and
• a hardware processor that adjusts at least one of the amount of the irradiation light, an offset of the detection signal adjuster, a characteristic straight line for calculating a glossiness, or a calculated glossiness based on a level of a detection signal output from the detection signal adjuster when the gain of the detection signal adjuster is changed.