Rapid proliferation of mobile devices with various sensors have enabled Participatory Mobile Sensing (PMS). Several PMS platforms provide multiple functions for various sensing purposes, but they are suffering from the open issues: limited use of their functions for a specific scenario/case and requiring technical knowledge for organizers. In this paper, we propose a novel PMS platform named ParmoSense for easily and flexibly collecting urban environmental information. To reduce the burden on both organizers and participants, in ParmoSense, we employ two novel features: modularization of functions and scenario-based PMS system description. For modularization, we provide the essential PMS functions as modules which can be easily chosen and combined for sensing in different scenarios. The scenario-based description feature allows organizers to easily and quickly set up a new participatory sensing instance and participants to easily install the corresponding scenario and participate in the sensing. Moreover, ParmoSense provides GUI tools as well for creating and distributing PMS system easily, editing and visualizing collected data quickly. It also provides multiple functions for encouraging participants' motivation for sustainable operation of the system. Through performance comparison with existing PMS platforms, we confirmed ParmoSense shows the best cost-performance in the perspective of the workload for preparing PMS system and varieties of functions. In addition, to evaluate the availability and usability of ParmoSense, we conducted 19 case studies, which have different locations, scales, and purposes, over 4 years with cooperation from ordinary citizens. Through the case studies and the questionnaire survey for participants and organizers, we confirmed that ParmoSense can be easily operated and participated by ordinary citizens including non-technical persons.