A microprocessor-based personal dosimeter with a silicon solid-state gamma-ray detector has been designed and built to provide reliable personal dosimetry. An IC (integrated circuit) card equipped in the dosimeter can exchange data with the microprocessor. Personal data concerning radiation dose control such as personal dose history and personal ID data are previously stored in the IC card. The dosimeter provides alarms on exceeding dose and working period limits in controlled areas and records the time differential dose data which can be used for the analysis of working procedures to minimize the personal dose in the controlled areas. The data stored in the IC card while the dosimeter is being used can be read by an external computer and used in preparing documents for personal dose control. These functions were confirmed by trial use in a nuclear power plant. >