In this paper, to monitor fugitive dust in construction sites, we propose a portable and inexpensive measurement system that can accurately measure the mass concentration of the total suspended particles (TSPs, that is, particles smaller than 50 μ m) in real time. The proposed system can measure the real-time mass concentration of the TSPs, which cannot be measured by conventional mass concentration measurement devices. It has four components: (1) particle collection section, (2) temperature and humidity measurement section, (3) particle measurement section, and (4) signal-processing circuit. When particles of different sizes reach the proposed system, they are selectively collected based on their size in the collection section. Thereafter, the collected particles reach the particle measurement section via the temperature and humidity measurement section. The particles are detected in the particle measurement section, and the mass concentration is calculated in the signal-processing circuit. Further, we analyzed the characteristics of each section, and the measurement results of the proposed system were compared using a filter-based gravity method. The calculated mass concentration of the TSPs corresponds to the results measured obtaining using the filter-based gravity method. Moreover, field test results indicate that the proposed system was successfully applied in construction sites.