The first batch of about 400,000 doses arrived on Friday at Narita airport to the east of Tokyo on an All Nippon Airways co. flight from Brussels.
Before the approval, the health ministry panel on Friday evening gave the greenlight given the vaccine, jointly developed by Pfizer and its German partner BioNTech SE, has already been used in several countries.
The Japanese government has sped up administrative procedures, considering starting vaccinations on Wednesday for around 20,000 doctors and nurses who have agreed to be vaccinated.
Health minister Norihisa Tamura has said earlier in the day that assuming the panel finds no issues with the vaccine, he will "immediately approve it so that inoculations can begin right away."
The country aims to begin vaccinating the general public against COVID-19 in May, two months before the postponed Olympics, after inoculating medical workers and the most vulnerable, according to local media reports.
The vaccination process is slated to start with medical workers, then people aged 65 or older from late March, followed by people with pre-existing conditions and those caring for the elderly.
Around 10,000 medical workers are in line to get the free inoculations first, followed by 50 million most at-risk people, according to government officials.