M. Qasim Mathar was born in Makasar on August 21, 1947. His big family is Bugis, one of major ethnic in South Sulawesi. His father, Mahmud Mathar, is a local trader, while his mother, Rukiah H. Abubakar, is a house-wife. He studied until year 5 of elementary school in where he was born. Because when his father faced economic problems which made him brought Mathar's family moved to his home town, Rappang, a small town about 188 km north of Makasar (now its in District of Sidenreng Rappang or Sidrap). However, he and one of his sisters remained live in his grandfather's house in Makasar until new academic year.
He completed his elementary school in 1960. He intended to enroll to Economic Junior High School (Sekolah Menengah Ekonomi Pertama), however, based on suggestion of his uncle and his auntie, he changed his mind and finally enrolled to Muhammadiyah Junior High School. Muhammadiyah, one of big Muslim organization in Indonesia, had strong influence and it owned some prominent schools in Rappang. His father is also an activist of Muhammadiyah.
He held both State and Muhammadiyah Junior Schools (SMP) certificate completed in 1963. He continued his study in Religious Teacher High School or Pendidikan Guru Agama Lengkap (PGAL) in Rappang. At the same time, Committee of Muhammadiyah District of Sulawesi also established Islamic Boarding School or Pesantren for Islamic Preacher Training (Pesantren Pendidikan Ulama) in Rappang, which its students recruited from districts in South Sulawesi where Muhammadiyah existed. Qasim Mathar and his classmates in PGAL also enrolled to the pesantren. He spent his time from morning to the day studied in PGAL , while in the evening until morning he studied in pesantren. Like other santri (students in pesantren), he lived in pesantren (boarding house).
It was in 1965, a year when the Indonesia Communist Party or PKI tried coup d'etat to the legitimate government, when he was in last year in PGAL and second year in pesantren. At that time there was no television, he up dated himself with the current political situation by listening radio and reading paper as well as discussed it with people who had just come from Makasar. He pursued his bachelor degree (S1) in Faculty of Ushuludin (Islamic Religious Study) State Institute for Islamic Study or IAIN Alaudin in Makasar. He held master (S2) and doctoral degree (S3) from State Institute for Islamic Study (IAIN) Syarif Hidayatullah Ciputat Jakarta in 1997. He dedicated his career as a lecturer in his alma mater which is now called State University of Islamic Study (UIN) Alaudin Makasar.
He married to a librarian, Dra. Sitti Nursiah Hamid, and has 9 children.