Shares in Mitsubishi Materials plunged more than eight percent on Friday after it admitted to falsifying product data, the latest major Japanese firm to acknowledge problems with quality control.
Stock in the Nikkei-225-listed firm was down 330 yen (8.06 percent) as the market neared the close on Friday, with the wider market fractionally in the green.
Company boss Akira Takeuchi was due to brief reporters on the scandal after the market close.
The firm said in a statement Thursday the affected products included rubber sealing materials used for packing and gaskets, often used to prevent leaks of liquid or gas from pipes in a wide variety of industries including aerospace and automobiles.
The scandal also affected brass strip products for cars and other products, it said.
Mitsubishi Materials said its subsidiaries falsified specification data before shipping some of its products to clients.
It added the company is working with affected clients to ensure the safety of their products.
The admission came after Japanese consumers saw a series of quality control and governance lapses at major firms including Kobe Steel, Nissan and Subaru.
Kobe Steel has admitted falsifying strength and quality data for a string of products shipped to hundreds of clients, from automakers to plane manufacturers.
Nissan recalled some 1.2 million vehicles after admitting in October that staff without proper authorisation had conducted final inspections on some vehicles intended for the domestic market before they were shipped to dealers.
Subaru also recalled nearly 400,000 vehicles from its domestic market after admitting that it also allowed uncertified staff to conduct vehicle inspections.