Positive Schick's test indicates that person is -
Positive test means that person is susceptible to diphtheria: So immunization is required.
Shick Test

Ref: Apurba Sastry’s Essentials of Medical Microbiology 1/e p248, Ananthanarayan 9/e p 241
Immune to diphtheria
Hypersensitive to diphtheria
Susceptible to diphtheria
Carrier of diphtheria